STYLE GUIDE
UNIT OPERATIONS/BIOPROCESS UNIT OPERATIONS:
ChBE 4200/4210
Fall 2023
Table of Contents
Background ...................................................................................................................... 2
Format, Font, and Word Limits ....................................................................................... 4
Abstract ............................................................................................................................ 5
Introduction ..................................................................................................................... 8
Theory ............................................................................................................................ 11
Experimental Apparatus and Procedure ........................................................................ 15
Results and Discussion .................................................................................................. 18
Conclusions & Recommendations................................................................................. 22
References ..................................................................................................................... 25
Nomenclature................................................................................................................. 30
Appendices .................................................................................................................... 32
Lab Report Examples .................................................................................................... 33
Appendix A: Scientific Writing & Format Specs ......................................................... 52
Appendix B: In-Text Citations ..................................................................................... 59
Appendix C: Writing - Style & Grammar .................................................................... 60
Appendix D: Other Standard Writing Conventions ..................................................... 62
Appendix E: Tables and Figures ................................................................................... 70
Appendix F: Transitional Words and Phrases ............................................................... 75
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Background
As a chemical engineer, communicating the process and results of your experimental
work is as important as the work itself. In fact, if you do not share your process and results with
the larger community (i.e., your co-workers, your boss, your professional peers), the work itself
ceases to have value. A written lab report is one way of documenting and disseminating the
details of your research. Oral presentations and posters are other methods. However, just
“writing up” an experiment is not adequate; the quality of the writing matters, as does the style of
the prose and the format and design of the report. Poor writing or sloppy document design can
interfere with, or even negate, the impact of meaningful content.
Although format and design specifics can vary from organization to organization within
the field of chemical engineering, this manual guides you through the specifics of formatting,
structuring, writing, and editing your lab reports for this course. It also offers some handy tips
for improving the overall quality of your writing.
Audience & Lab Reports (generally)
In telling any story, what you tell, as well as how much context and detail you include,
depends on who the listener is. For example, if you ask a friend to meet you at Tech Tower
before a football game, you do not have to describe what Tech Tower looks like and where it is if
your friend is a Tech student, but if he or she isn’t, you would need to include more detail and
direction. In writing your lab report, you need to consider such issues. Who would read a lab
report? Why? And how much do they already know about the subject?
In general, people would read a report such as the ones you will write because they may
find it necessary to undertake a similar study, or they may want to use your findings to help
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make design or purchase decisions. Given this information, you can assume that your readers
have a basic understanding of general chemical engineering principles—for example, fluid,
mass, and heat transfer; thermodynamics; reactor design; process control; and so on. In short,
any individual with an average knowledge of chemical engineering concepts should be able to
read and understand your report without difficulty. (Imagine a ChBE or other engineering
graduate or an MBA working in a ChBE industry.) However, you should recall that even a
qualified chemical engineer may have forgotten the specifics of some area of this field. Thus,
you may need to remind them of some of the details or clarify the operation of specific units.
Rhetorical Context for ChBE 4200/4210 (your specific audience & purpose)
What is rhetorical context? It is simply the situation that surrounds your act of writing.
What are you writing? Why? For the purposes of this course, you are not a student when you
write your lab reports. Instead, you are to assume that you are an engineer working for a
company that has just purchased several experimental set-ups. Each set-up was designed to
measure the physical or chemical properties of a system or characterize a unit operation, reaction
process, or transport process. A manual of suggested experiments was provided. Your boss has
asked you to work in a team of three (or two) to evaluate the performance of each set-up by
conducting an experimental study in each over a range of specified conditions. You are then to
report back on the behavior of the system studied and analyze and characterize the phenomena as
directed by the lab manual. You should also convey the “bottom line,” or overall conclusion,
reached from your experiment(s), as well as two or three relevant recommendations for
improvement of the current study or for future phases of experimentation.
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Format, Font, and Word Limits
FORMAT:
• Left aligned (click “Align Left” in the top ribbon of Word)
• 1.5 line spacing
• Page numbers at bottom center or bottom right
FONT:
Main text: 11 or 12 pt. Times New Roman font
Table titles and figure captions: 10 pt. Times New Roman
No title page. Instead, just put title page info at top of the first page—see the first Lab Report
Example in the Style Guide for details.)
No table of contents.
SECTIONS
Abstract
Introduction
Theory
Apparatus and Procedure
Results & Discussion
WORD LIMITS* and other details
Conclusions & Recommendations
References
275 words
170 words
275 words
150 words
550-650 words (no more than 4 tables or
figures in R&D)
160 words
At least THREE outside references (not
Nomenclature
Appendix A: Title of Appendix
required.
1.5 line spacing
No word limit.
No word limit on appendices.
including Safety Data Sheets [SDS] or lab manual) are
Appendix B: Title of Appendix
(other appendices as needed)
*Note: Word limits do NOT include tables (titles & content) or figure captions.
*Except for the Abstract, which must be no longer than 275 words, you may go over each listed
word limit by 10% without any penalty.
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Abstract - Word limit = 275 words
The Abstract is a focused summary of the report; it provides readers with a glimpse of the entire
report in a shortened form. Therefore, it is one of the most important parts. It helps a reader decide
whether to read, skim, or skip the document or to pass it along to others. To accomplish these
goals, the abstract must answer these questions:
-
What was done, and why? (should include one or two introductory sentences
putting the experiment and its field in perspective, thus motivating the study; a brief
description of apparatus; statement of objective(s); and a brief description of
methods, including range of conditions if appropriate)
-
What were the results, and what conclusions were drawn from them? (includes
significant results with some level of quantification, comparison to theory/model
expectations, error analysis, key conclusions, and overall “bottom line” or takeaway
from experiment)
Abstracts are typically single-paragraph discussions, and they stand completely
alone. In this way, they would be understandable even if published by themselves, as they often
are in databases of abstracts. Given this constraint, the abstract never specifically refers to any
figure or item in the report and cannot contain references to the literature or lab manual; instead,
it contains its own independent quantification and discussion of the results.
The first part of the abstract should constitute roughly 1/3 of the entire abstract.
This part provides motivation for the study and gives the experimental objectives as well as a
brief overview of the apparatus and procedure. It should also mention any critically important
issues, such as any difficulties that prevented meaningful interpretation of some of the results.
The abstract should begin with an orienting sentence (one that provides some perspective on the
significance or motivation behind the work). This sentence should be informative: a good
opener clearly explains significance and motivates the study. Generic sentences such as
“Packed-bed absorption is important in chemical engineering” should be avoided. A more
effective example would give a specific feature or benefit that explains why packed-bed
absorption is important, perhaps in a particular field or process. See sample reports for examples.
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The second, and most important, part of the abstract should be about 2/3 of the
section. Here, you should discuss the results, conclusions, and takeaway of the experiment.
In the abstract, the discussion of results should be both quantitative and qualitative.
Appropriate levels of quantification vary depending on the experiment. For example, if the goal
of the lab was to determine one or two quantities, then these should be placed in the abstract with
their statistical confidence intervals. If several experiments were performed, you may quantify
by giving ranges of key results or by quantifying the “best case” scenario at the optimal
conditions. A general description of the observed trends in the data or of how the results
compared to a model or theory should be included. However, even this general description
can be quantitative. For example, phrases like “…the data were similar to the model” should
be avoided in place of more quantitative phrases such as “… all data points were within 5% of
the model predictions.” or “…the root mean square average of the difference between the data
points and the same points predicted by the model was 7.4%.”
The abstract should also include the key conclusions that indicate what was learned
from the experiment. In this context, major sources of error may be included if your results
departed significantly from expectations.
The final sentence in the Abstract should be the takeaway or “bottom line.” (See
Conclusions and Recommendations or the example on the next page for a description of what we
mean by “bottom line.”)
Generally, recommendations do not belong in the abstract.
While this section provides a summary of the entire report, it cannot exceed 275 words.
Therefore, you must spend your words wisely and make sure each one counts. Be sure to answer
WHAT, WHY, HOW, and SO WHAT? See abstracts in the Lab Report Examples or in
technical journals for examples.
Below is a good example of an abstract. (This example has 275 words.)
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First 1-2
sentences
lend
perspective
and provide
motivation
for the study.
Next, the
experimental
apparatus is
briefly
described.
Statement
of
objective(s)
provides
roadmap for
the rest of
the abstract.
Briefly
describe how
the objectives
were
accomplished.
Quantitative
and qualitative
presentation of
key results,
along with brief
interpretation.
(Note: when
reporting
averages, the
conf. interval
should be
given.)
Quantitative
comparison
to literature
or theoretical
value.
Key
conclusions
from results,
including most
significant
sources of
error.
Abstract should
end with the
“bottom line”
or takeaway –
why or how
would your
findings be
useful to
anyone? (It is
useful to “circle
back” to your
motivation
here.)
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Introduction – Word limit = 170 words
The purpose of the Introduction is to provide motivation for the study, to help orient
readers, and to give them relevant background information—all of this material should provide a
natural lead-in to the experimental objectives, which you should present directly in the final
paragraph of the Intro. Therefore, before writing the Introduction, you must first determine what
your experimental objectives are! (See more on objectives on the next page.)
In your lab reports, you will usually write an Introduction that consists of two
paragraphs:
Para. 1:
motivation for study; definition of operation; significance of operation in
industrial applications (with at least one specific example); benefits and
drawbacks (or limitations)
The first paragraph is generally written in PRESENT tense.
Para. 2:
relevant physical and chemical characteristics; statement of objectives;
very brief statement of how objectives were achieved.
The relevant physical/chemical characteristics are generally written in
PRESENT tense.
The objectives and procedure are written in PAST tense.
In the first paragraph of the Intro, you need to provide motivation for this experiment.
You can do this by giving background on the operation or mechanism being studied and
indicating why it is important to study. Define the operation and explain its significance in an
industry related to chemical engineering: Which industries use it and why? How do they use
it? What advantages does this operation or mechanism have over others, and what disadvantages
or limitations might it have? Ideally, this paragraph should foreshadow the objective(s) of the
experiment. (E.g., if your objective has to do with determining the effects of flooding on
efficiency, your first paragraph should briefly indicate how and why flooding is a central concern
for this particular operation, but not actually state your objective specifically at this point.) A
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specific and relevant industrial example is helpful in the first paragraph. For example, "Because
of its……., the centrifugal pump is often used for ..." Try to choose examples that involve
chemical engineering or other relevant industries. Be sure to cite any references you may have
for this information, including the lab manual. Failure to do so constitutes plagiarism.
Although more space for background information is available in the introduction than in
the abstract, economy of prose is important in technical writing. Sentences that are too generic
or state the obvious should be avoided. For example, the opening sentence “Fractional
distillation is very important in separating chemical substances” is generic because the term
“Fractional distillation” can be replaced by a variety of unit operations.
Rule of thumb: if you’re going to say that something is important, you must also tell
us why it is important.
In the second paragraph, you need to:
o briefly describe the important physical and chemical characteristics of the
operation, focusing on those that are particularly relevant to your analysis;
o state your objective(s) clearly and thoroughly; and
o briefly indicate how you met those objectives.
If you used your first paragraph to foreshadow your objectives, this next paragraph should come
as no surprise to the reader. Make the wording of your objective as specific as possible—and
remember that a good objective must be measurable. (Hint: “the objective was to
characterize/study/observe the performance of [xxx apparatus]” is neither specific nor
measurable). Beware of copying the objective as stated in the lab manual—in most cases this is
a general goal, and it is your job to whittle it down to a specific, measurable objective. You also
need to provide one or two sentences to very briefly describe the methods used to meet your
objective(s). You should NOT present any results in this section.
** Information in this section should be organized from general => specific, like an inverted
triangle.
**The purpose of the Intro is to give perspective and background on why the objectives and the
study are important. In other words, it needs to motivate the study.
Below is a good example of an introduction.
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First two
sentences
lend
perspective
and provide
motivation
for the study.
Second
paragraph
begins with
relevant
properties
and
parameters.
TENSE: Use
PRESENT
tense for 1st
paragraph of
the intro.
Third
sentence
indicates
benefits of
LLE and an
industrial
application.
End of 1st
paragraph
states a
relevant
limitation of
LLE.
TENSE: Use PRESENT tense for “key properties”
After stating
relevant
properties,
the next
sentence
gives the
objective.
The second
paragraph
ends with a
brief
description
of how the
objectives
were
achieved.
(Tip:
objective
should be
specific and
measurable.)
TENSE: Use
PAST tense
for objectives
and procedure
in the 2nd para
of the intro.
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Theory - Word limit = 275 words
The Theory section presents the models (usually one or more equation/s) used to analyze
your experimental data. The purpose of this section is to lay out an interpretive model; it tells
your reader what theories and equations are important to interpret data from the experiment
(specifically, what theories and equations are being used). When you write this section, be sure
to move logically from one equation to the next—use transitional words and phrases.
Here are some key guidelines to follow in the theory section:
•
Because this section is devoted to theory, it is written in the PRESENT TENSE.
•
You should also avoid using the general “we” in this section, in the sense of “we
need to examine,” “Here, we can see,” and so forth.
•
As with the introduction and abstract, economy of prose dictates that obvious or
generic sentences should be avoided. Sentences like “In order to understand
reactive distillation, one must first understand the theory behind reactive
distillation” are generic and do not add value to the section.
•
Avoid repeating much of what is in the laboratory manual. Simply include the
important final equations, along with a clear yet concise explanation of the main
theory or model being used and any important assumptions or limitations.
•
Any additional equations that are needed should be detailed in an appendix—be
sure to reference (“call out”) this appendix in your main Theory section.
If an equation only has a few variables, you can define them in the Theory section as well
as in the Nomenclature section. However, if your equation has more than three or four variables,
you might not have room to define them all in the Theory section. In this case, simply refer the
reader to the Nomenclature section for definition of all terms in the equations. Either way, you
will always need to have a Nomenclature section in each lab report.
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To achieve its purpose, the Theory section needs to
•
•
•
briefly clarify engineering concepts that are relevant to your analysis and show the
development of the model used to analyze your data.
include all assumptions, previous work that supports the model, and any limitations if they
are known; and
cite sources (including the lab manual) for all equations.
The Theory section should NOT be a carbon copy of the lab manual. Your goal is to
show an understanding of the theory or model, not just to copy a bunch of equations.
The word limit for the Theory section is 275 words.
As for each section in the lab, this section should begin with a sentence that lends perspective
to the Theory section relative to the lab report as a whole. This opening matter should be as
specific and informative as possible. Do NOT repeat information from the introduction, and do
NOT use generic statements such as “In order to understand this lab, it is necessary to understand
the theory behind it.”
Here is an example of a good opening passage for the Theory section:
Many processes that involve phase changes, such as evaporative cooling, are governed
by the balance between the heat loss due to evaporation and the convective heating caused by
the evaporative cooling. This experiment focuses on this balance in the evaporative cooling of
water on a copper cylinder. The energy balance for such a process is written as….
Final note: If you took any equations from the lab manual or any other source, be sure to
include an in-text citation and a corresponding entry in your References. Failure to do so may
constitute plagiarism.
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The theory
section
should begin
with an
orienting
sentence.
One (but not
the only!)
logical
starting point
is describing
the driving
force for a
process.
Don’t repeat
material
from the
Intro.
Center all
equations.
Put equation
numbers in
parentheses
flush with
right-hand
margin.
(You may use
invisible
tables to
accomplish
the correct
format.)
You must
cite any
equations or
other
material
from the lab
manual or
other
sources.
You may refer
reader to
Nomenclature
for definition
of terms.
Note key
assumptions
and
limitations
of the
theoretical
model.
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Including
transitions
and
paragraph
breaks in
this section
will improve
the logical
flow.
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Experimental Apparatus and Procedure – Word Limit = 150 words
This section describes the apparatus used to conduct the experiment and explains how the
equipment was used to do the experiment.
This section can be broken down into two main paragraphs: description of apparatus, and
description of procedure and key safety issues. Please note: The entire Apparatus and
Procedure section should not exceed 150 words. When possible, use SI units throughout the
report.
Paragraph 1:
Description of the apparatus. Give a brief, general description, no more than one short
paragraph in length. This description of the apparatus can be in either PRESENT or PAST tense,
depending on the context.
Example of apparatus description: (92 words)
In this experiment, a countercurrent Karr column with reciprocating sieve plates was
used. The column was 1 in. in diameter and 6 ft in length, and each end of the column had a 2
in. diameter disengagement section. The water and diesel were pumped from storage tanks
through calibrated flowmeters. A needle valve was used to maintain a constant interface
between the organic and aqueous phases. The extract flowed from the bottom of the column
while the raffinate flowed from the top of the column. Figure 2A in Appendix A details the
apparatus.
Note: You must include a clearly labeled schematic diagram of the apparatus (or the
relevant portion thereof) in this section, or in an appendix (but you need to call out the
appendix). You may use a photo of the lab equipment to supplement, but not replace, the
diagram! Be sure to include a citation for the diagram if it was taken from the lab manual or any
other source.
Paragraph 2: References the procedure and describes key safety issues.
This paragraph should begin with some version of this sentence: The experimental
procedure was taken from the UO Lab Manual1 and followed without any deviations / followed
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with the exception of several deviations. Be sure to reference the lab manual. If there were any
significant deviations, those should be described next.
You should also include any key parameters or conditions, especially those not specified
in the lab manual, such as the experimental conditions used, flow rates, temperatures, and so on.
Finally, any relevant safety issues should be briefly discussed, and you must cite the SDS for any
chemicals (other than air and water) used in the experiment. (NOTE: the SDS references do
not count towards the requirement for three outside references!)
You also must include a sentence mentioning the JSA and include a reference to the
Appendix that contains your JSA.
Verb Tense for Procedure Description:
•
Procedure description should be mainly past tense, with the possibility of present
tense when discussing chemical hazards, etc.
Experimental Apparatus and Procedure (good example)
(Note: the main goal was to investigate a process of mass and convective heat transfer occurring
simultaneously)
The equipment for the simultaneous heat and mass transfer experiment consisted of a
stand outfitted with a clamp placed in front of a small wind tunnel. Other equipment included a
bare copper cylinder with a diameter of 5 cm, a gauze-wrapped copper cylinder with a diameter
of 3 cm, a thermocouple, a stopwatch, an ice water bath, and a room-temperature water bath.
The copper cylinders had small holes in the end where the probe of the thermocouple was
placed. The experimental apparatus is shown in Figure 1.
[Figure 1. Diagram of apparatus goes here, or in an appendix (must call out the
appendix). Remember to include citation at the end of the caption if taken from an outside
source, including the lab manual!
To meet the experimental objective, we followed the procedure as outlined in the UO Lab
Manual1 but with several deviations:
•
(describe first deviation)
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•
(describe second deviation)
•
(etc., etc.)
Standard safety protocol, including the use of safety glasses, closed-toe shoes, lab coats, masks,
and gloves, was followed. A job safety analysis (JSA) was conducted before performing this
experiment (see Appendix A).
(Note for at-home or simulated labs): We realize that you may not actually wear safety glasses
or other PPE for computer simulations or at-home labs. However, we do want to reinforce
concepts of safety during experimentation, so please still include a brief discussion of safety,
including any relevant safety issues and standard safety protocol that would be followed in an
actual wet lab, as shown in these examples.)
Note: For a lab in which chemicals are used or in which there are other safety concerns
(such as high temperatures, rotating impellers, slipping hazards, etc.), the safety paragraph
should follow the basic structure below:
The main safety concerns in this experiment were that sodium hydroxide is a strong base and is
corrosive, and ethyl acetate is flammable.2 For other potential chemical hazards, refer to the
safety data sheets (SDS) listed in the References section.3,4 Standard safety protocol, including
the use of safety glasses, closed-toe shoes, lab coats, masks, and gloves, was followed. A job
safety analysis (JSA) was conducted before performing this experiment (see Appendix A).
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Results and Discussion – Word Limit = 550-650 words
The purpose of this section is to convey what you found in performing the experiment
and to explain the significance of those findings. This section also compares the results you
obtained with those you expected from literature correlations or theoretical models. It also
explains error—it should discuss the source of errors and should also quantify and characterize
their impact on the experiment. To reach these goals, this section needs to:
•
present and explain your results in a clear, well-organized, and concise manner
(use figures and tables to present information efficiently); make sure that you
provide all results that are requested in the lab manual, as well as any others that
you feel are appropriate and relevant to your objectives.
•
discuss and analyze the significance of those results, including how they relate to
each other and how they compare to the theory/model. In this process, you should
describe significant sources of error and quantify the effect those errors had on the
experimental results. Use statistical analysis tools where relevant and
appropriate.
How should you go about organizing information in the Results and Discussion section?
First, briefly summarize the first objective you’re going to cover, and briefly review the
first step of the analysis. You do not need to recap procedural details here.
Then, you may wish to present a figure or table of the raw data (or a typical subset) to
convey information about scatter, the range over which data were taken, magnitudes, and so on.
However, please avoid large tables with tons of data—these are best placed in the appendix, not
here.
Next, you should break this information into its significant component parts and focus on
each part individually. Your discussion/analysis should occur at the same time.
The section may conclude with some discussion of error (although it often makes more
sense to discuss error as you go along). For example, if you find that your results generally are
not what you expected—or are not ideal—you must discuss the discrepancies. What could
account for them? What caused you to suspect these sources? How exactly did these
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discrepancies affect your results? Provide evidence to support your claims, quantify the impact
of various sources of error, and characterize the impact of any erroneous assumptions.
You are limited to no more than FOUR tables and figures (total) in the Results &
Discussion section. We do want you to use tables and figures (usually, you should have at least
two in this section), but we don’t want you to go overboard in such a short report. The best
strategy is to decide which tables and figures do the best job of illustrating the key points you
wish to convey. All other relevant tables and figures may be placed in an appendix and called out
in the main text.
In working through each part of your data, follow these steps:
1. Introduce each figure or table (briefly) before the reader sees it (e.g., “Table II shows
the relationship between time and temperature.”).
2. Insert the figure or table. (See Appendix E: Figures and Tables for format
requirements)
a. Note that figures and tables should be centered on the page.
b. Tables and figures should be no more than ½ page in height. Most should
be no more than 1/3 page in height.
3. After presenting the figure or table, it must then be explained:
a. First, point out significant features or trends; tell your readers what you want
them to see in the figure or table (e.g., “Figure 4 shows that as time increased,
temperature decreased.”) and discuss the trends that are shown. Note: If you
fit your curve to a specific subset of your data points, explain your reasoning.
Also, indicate your reasoning behind any corrected or omitted data.
b. Then, you need to discuss the importance of your findings—both generally
AND in relation to your theory or model. Do your results make sense? If so,
why? If not, why not? Do your results match theory or model? If not, give
reasons for the discrepancy. (e.g., “The reciprocal relationship between time
and temperature reveals . . .This relationship between time and temperature
was expected based on…. It shows . . .”). Be sure to discuss any specific
error and the effect that such error might have had on the particular part of the
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data on which you are focusing. Quantifying the impact of error on your
results is quite helpful to the reader as well.
Use significant figures in all of your results (to review the conventions of significant
figures, see Felder and Rousseau, 2000). You should know how precise your measurements are;
the significant figures must reflect the precision of the data. Also, in reporting the average of
repeated data, include the confidence interval, and where possible apply propagation of error
analysis. When possible, use SI units throughout the report.
Before you can write the Results and Discussion section, you must complete the sample
calculations (include in an appendix). You will need to mention any data that were rejected in
the calculations and any data that may be erroneous. However, you do not want to inundate
readers with numbers and figures; rather, escort them carefully through the logic of the
calculations. It is much easier to grade a report that presents sample calculations clearly,
thoroughly, and logically.
Here are examples of opening sentences for the Results and Discussion section:
To determine the effect of horsepower on the performance of the laboratory pump, the
first step was…
To meet the first objective of finding the oxygen permeance and oxygen/nitrogen
selectivity of the membrane, we performed two trials…
Again, the general format of this section for each result is as follows:
1-
To determine ……, we measured / calculated / etc. …
2-
Figure 1 illustrates the relationship between….
(Note: if the figure ends up on the following page, you may write “Figure 1 below
illustrates…” Otherwise, you don’t need to write “below.”
3-
[Insert Figure 1]
4-
As Figure 1 shows, …
5-
These results suggest/indicate that…
6-
The results were expected per theory/model, which states… OR, the results were
unexpected, and here’s what we think caused the discrepancy…
In this section, you should thoroughly analyze and explain your results, possible sources
of error, the degree of confidence, and the implication of your observations. Error analysis
should be quantitative whenever possible. Even if your results are poor, if you can explain them
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well and account for discrepancies, you can still get a good grade. Conversely, good results,
particularly if presented poorly, do not guarantee a good grade.
Transitions
The skillful use of transitional words, phrases, and sentences will make the difference
between a report that is easy to follow and a report that is not. Thus, you should try to lead your
reader through the discussion of results with sentences like “After determining that flow rate
increased with…, we next analyzed the relationship between…” For example:
Once the heat transfer coefficient was calculated, the next step in creating a model for
the simultaneous heat and mass transfer cooling of a copper rod was to determine the masstransfer coefficient. This coefficient was determined by…
Determining the mass transfer coefficient provided the data necessary to formulate a
model of the cooling process seen in Figure 3. To derive the model, …
After deriving the model, we then compared it with our experimental data. Figure 5
shows this comparison.
** These transitions make reading through the analysis and discussion of the results much
easier. They are like road signs telling you where you’ve been, where you are, and where you’re
going, and how the individual results are related to and build upon each other.
**See Appendix F: Transitional Words and Phrases for examples of transitions.
**Be sure to use the correct tense. See Appendix A for a discussion of tense so you can
understand what tense to use in this section. Generally, if you are describing a result or behavior
that occurred in the experiment, you should use PAST tense (e.g., “In the first trial,
concentration of NaOH increased with impeller speed.”) But when you switch to discussing
whether that result makes sense, you may need to switch to PRESENT tense (e.g., “This trend
makes sense because an increased impeller speed should increase mixing, thus leading to
increased concentration.”)
The length of the Results and Discussion section will vary per experiment (aim for around 550
words, although up to 650 words will be accepted). It should be the longest and richest section
of the report.
In Results & Discussion, you should keep procedural and calculation details to a minimum as
much as possible. The main focus should be on your results and what they mean—spending
more time on the most important results. You can also use appendices to explain how you
calculated certain values—just be sure to “call out” the appendix in the main body of the report.
Please see Lab Report Examples for good examples of Results & Discussion.
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Conclusions & Recommendations – Word Limit = 160 words
The Conclusions & Recommendations section presents a final assessment of the
importance of the experiment and its results. This section typically consists of two paragraphs.
The first paragraph should be devoted to conclusions, and the second paragraph should describe
two or three relevant recommendations.
Paragraph 1:
The first paragraph should give your reader a final, broader sense of the experiment and
its success or problems. Here, you are presenting key conclusions that are supported by your
results and analysis. Ultimately, how well did the experiment perform? Did the results compare
well with expected or ideal results? How reliable were your data? Remember, the goal is to
state conclusions based on your key results and to provide a broader context, NOT to
simply repeat your results! No brand-new results should be presented in this section. In other
words, don’t “save” results for this section, and don’t bring up new ideas out of the blue.
A helpful rule of thumb is that for each objective you presented in the Introduction,
you should have at least one conclusion. In this way, you show that you have indeed achieved
your objectives and have learned something about each aspect of the experiment.
The final sentence of the 1st paragraph in this section (your Conclusions paragraph)
should address the “bottom line” or “takeaway”—it should answer the question “so
what?” about your results. Try asking yourself these questions when deciding on your takeaway:
•
Why would these results be relevant or applicable to the chemical industry or other
industries?
•
Why would anyone care about your results? How could they be useful?
•
How could someone apply some aspect of your results to a real-world problem?
This “bottom line” is something that should also appear at the end of your abstract but would not
be mentioned explicitly in any other section. It should, however, flow naturally from the results
that you obtained. You may also try to link this “bottom line” to the motivation that you brought
up in the Introduction, thus “closing the circle.”
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Paragraph 2:
The second paragraph focuses on recommendations. You should include two or three
relevant recommendations in this section. These may offer non-generic suggestions for
mitigating sources of error in the experiment, as well as suggesting what the next logical stage of
experimentation might be. For recommendations that suggest improving data accuracy or
precision, statements like “we recommend XX repetitions of the entire experiment XX for greater
statistical accuracy” are too generic and therefore not suitable as recommendations. On the other
hand, it is appropriate to identify specific aspects of the experiments where improvements would
be particularly beneficial.
For example:
This experiment was successful in showing that efficiency of a laboratory centrifugal
pump was directly related to…. We discovered that…. The data demonstrated internal
consistency since……. Furthermore, the data were shown to be accurate based on……However,
a calibration error caused…. Overall, the experiment indicated that this pump would/would not
be useful in an industrial process with …. requirements.
For the future, we recommend improving this experiment by…. An additional
recommendation for future stages of experimentation is…
** What did you find? What did you learn? What are the sources of error? Degree of
confidence? What are the implications of your observations? What’s your OVERALL “bottom
line”? Don’t forget to provide evidence (quantitative, if possible) for your claims
** In this section, you should draw conclusions based on key results and give recommendations
for improvement of the current study (or logical next steps in experimentation).
Below is a good example of a Conclusions & Recommendations section.
Conclusions & Recommendations (about 165 words)
In this experiment, the effect of oscillation rate on the separation of propionic acid and
diesel through liquid-liquid extraction was successfully determined. The percent of propionic acid
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removed increased with increasing plate oscillation rate, despite discrepancies in the mass balance
equations. Increases in the oscillation rates also correlated directly with the number of equilibrium
stages. Additionally, as the oscillation rate increased, the HETP and H0y values decreased.
However, experimental trends did not agree with published correlations because of differences in
operating conditions. Overall, results indicated that higher oscillation rates in an industrial LLE
process would increase mass transfer, but the correlations studied may be of limited use in
predicting the HETP.
Recommendations for this lab include researching and testing other literature correlations
that may be more accurate for this type of separation. One possibility is the XYZ correlation for
ABD systems.6 For the next stage of experimentation, we recommend performing the
experiment at oscillation rates above 210 min-1 to determine an optimal rate for mass transfer
efficiency.
Brief note about recommendations: ** Be careful of “whining” or sounding too
student-y (remember your rhetorical situation). You should not complain about the TA, or about
directions in the lab manual or problems you had doing the experiment because of the directions,
or about the experiment taking too long. Instead, offer your colleagues recommendations for
doing the experiment more efficiently or safely so as to achieve more accurate or conclusive
results. You can also suggest other methods of experimentation or analysis for the future, as
long as you tell us why you’re making the suggestion. As always, avoid generic and vague
statements.
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References
Because good research is a key part of any report, it is required that you include at least THREE
outside references in your report (i.e., references other than the lab manual and SDS). The SDS
websites should be cited in the Procedure section and included as references in your References
section, but they do NOT count towards this requirement. These outside references may include
textbooks, journal articles, books, online scholarly articles, academic websites, and so on. Just
make sure that you cite them properly, both within the text and in the References section. Citing
Wikipedia or About.com (or other such encyclopedic, non-peer-reviewed sites) is NOT
permitted. However, Wikipedia can be an excellent starting point in finding more credible
sources.
In this class, we will follow the ACS Reference style as explained in detail in The ACS
Guide to Scholarly Communication. In organizing the information in the References section,
please use the following “templates” to organize and punctuate the standard bibliographic
information. If some standard information is not available (e.g., an author), you should omit that
category (see examples under “Article in an anthology,” which has no author, and “On-line
Article or Web Site,” which has no author).
Note that each reference entry should end with a period.
Number your entries in the order in which they are first cited in the text.
The entire list of references should have 1.5 line spacing.
Guidelines:
•
For a book written or edited by one or more persons:
First author’s last name, first and middle initials; second author’s last name, first and middle
initials; etc. Title of Book, edition number.; Editor 1, Editor 2, Eds. (if an edited book); Publisher:
Place of Publication, Year; Page number(s) used.
EX.
Coulson, J.M.; Richardson, J.F. Chemical Engineering, 4th ed.; Elsevier: Oxford, 2005; p 34.
OR (for multiple pages):
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Coulson, J.M.; Richardson, J.F. Chemical Engineering, 4th ed.; Elsevier: Oxford, 2005; pp 1; 7;
34.
OR (for a page range):
Coulson, J.M.; Richardson, J.F. Chemical Engineering, 4th ed.; Elsevier: Oxford, 2005; pp 34-40.
NOTE: if authored by more than one person, list names in the order in which the names appear
on the book’s title page. Names of authors and editors should be listed as last name, first and
middle initials (skip the middle initial if not provided). Authors’ names are separated by a semicolon. Editors’ names are separated by commas. Be sure to include each author or editor, even if
there are more than three.
•
For the UO Lab Manual (the UO lab manual is considered to be an anthology):
Author’s last name, first and middle initials (note: for the UO lab manual, you should NOT list
authors). Title of Article. In Title of Book, edition number (if there is one); Publishing company:
Place of publication, Year; Volume number, page number(s).
EX.
Continuous Stirred-Tank Reactors. In Unit Operations Lab Manual; Georgia Tech: Atlanta, GA,
2023; p 4.
Continuous Stirred-Tank Reactors. In Unit Operations Lab Manual; Georgia Tech: Atlanta, GA,
2023; pp 4-6.
*Note that in the above examples, no author was listed for the article; therefore, this part of the
entry is omitted. Any time you cite the lab manual, you omit the author’s name.
• For an article in a journal:
First author’s last name, first initial and middle initial; second author’s last name, first and
middle initials; etc. Title of Article. Journal Title (or Abbreviation) Year, Volume (Issue number
or Month and date), Inclusive Pagination.
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(The journal title should be italicized and may contain approved library abbreviations. When in
doubt, use the full journal title. The year should be in bold. The volume number should be in
italics.)
EX.
Taveira, P.; Cruz, P.; Mendes, A. A Maxwell-Stefan Experiment. Chem. Eng. Educ. 2000
34 (1), 90-93.
• For a general web site:
(Although your source may not offer all of the following, include as much as possible.)
First author’s last name, first and middle initials; second author’s last name, first and middle
initials; etc. Title of Article/Document. Title of Site. URL (accessed Month, Day, Year).
For title of site, use the title found on the Web site itself. Add the words “Home Page” for
clarification when needed.
EX.
Smith, J.S; Floating Point Unit Operations. MIPS Technologies, Inc.
http://techpubs.sgi.com/library/tpl/cgi-bin/getdoc.cgi/ hdwr/bks/SGI_Developer/books/
R10K_UM/sgi_html/t5.Ver.2.0.book_313.html (accessed January 25, 2023).
•
For
a document retrieved from an agency or university web site:
First author’s last name, first and middle initials; second author’s last name, first and middle
initials; etc. Title of Document, Year. Title of Site. URL (accessed Month, Day, Year), other
identifying information, if any.
If an article is contained within a large and complex Web site, such as that for a university or
government agency, the host organization and the relevant program or department should be
identified BEFORE giving the URL and access date.
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EX.
Technology integration and publishing, 2001. Columbia University for Learning Technologies.
http://www.ilt.columbia.edu/tech-and-pub-past-projects/ (accessed January 21, 2023).
Try to avoid citing sources that will not be accessible to your reader. Examples include
class handouts/slides or your own lecture notes. It is ALWAYS preferable to go to the primary
source (e.g., the textbook for that class or another peer-reviewed source that contains the same
material).
However, there may be instances where you cannot access the information elsewhere. If so,
please use the format detailed below.
Note that it IS permissible to cite the UO Lab Manual (see above for how to cite it).
•
For PowerPoint slides or handouts from a class or presentation:
Presenter’s last name, first and middle initials. Title of Presentation. Presented in
Course/Conference Title, Place, Date.
EX.
Medford, A.J. Statistical Modeling. Presented in ChBE 2120, Georgia Tech, May 25, 2020.
Jones, J.M. Developments in Transdermal Drug Delivery. Presented at the 20th International
Conference on Drug Delivery, Montreal, Canada, June 12, 2019.
•
For your own lecture notes from a course:
Instructor’s last name, first initial. Course title lecture. Place, Date.
EX:
Breedveld, V. ChBE 3200 lecture. Georgia Tech, March 1, 2020.
In-text Citations
For information on citing material within the text, please see Appendix B of the Style Guide.
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Sample References section
Number your references in the order in which they are first cited in the text. Please
use 1.5 line spacing.
1. Taveira, P.; Cruz, P.; Mendes, A. A Maxwell-Stefan Experiment. Chem. Eng. Educ. 2000 34
(1), 90-93.
2. Geankoplis, C.J.; Hersel, A; Lepek, D. Transport Processes and Separation Process
Principles, 5th ed.; Pearson: New York, NY, 2018; pp 27-30.
3. Continuous Stirred-Tank Reactors. In Unit Operations Lab Manual; Georgia Tech: Atlanta,
GA, 2023; p 4.
4. Algebraic Solution of Equilibrium Stage Problems: The Kremser Equation.
www.cbu.edu/~rprice/lectures.kremser. html (accessed May 25, 2023).
5. Felder, R.; Rousseau, R.W. Elementary Principles of Chemical Processes, 3rd ed.; John Wiley
& Sons: New York, 2000; pp 4, 21.
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Nomenclature
The Nomenclature section provides a “key” to the symbols and units used in the lab report.
Please note that when possible, SI units should be used here, as well as throughout the report.
Items should be listed in alphabetical order, putting all English symbols first, then Greek.
Note: EVERY report MUST have a Nomenclature section (even the Gummy Bear report!)
Sample Nomenclature
Symbol
Definition
Units
A
surface area
m2
Cpair
heat capacity of air
J/kg/K
Cpc
heat capacity of copper
J/kg/K
Cpw
heat capacity of water
J/kg/K
DAB
diffusivity of an air water system
m2/s
Eacc
energy accumulated in a system
J
Eg
energy generated in a system
J
Ein
energy entering a system
J
Eout
energy leaving a system
J
h
convective heat transfer coefficient
W/K/m2
Hfg
mole heat of vaporization of water
J/kg
Jix
molal flux relative to molal average velocity
-
Kair
thermal conductivity of air
W/K/m2
Kc
thermal conductivity of copper
W/K/m2
Kw
thermal conductivity of water
W/K/m2
Lc
length of copper cylinder
m
M
molecular weight
g/mol
Npr
Prandtl number
-
Nsc
Schmidt number
-
Nw
molal flux of water relative to stationary coordinates
J/m2/s
P
atmospheric pressure
mmHg
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pw
partial pressure of water
mmHg
Pw
vapor pressure of water
mmHg
T
temperature of cylinder at time t
o
C
TAir
air temperature
o
C
Tdb
dry bulb temperature
o
C
T1
initial temperature of copper
o
C
U
molal average velocity
-
V
volume
m2
x
mole fraction of water vapor at surface of gauze
-
xAir
mole fraction of water vapor in room air
-
yAir
mole fraction of air
-
ρc
density of copper
kg/m3
ρw
density of water
kg/m3
μair
viscosity of air
kg/m/s
μw
viscosity of water
kg/m/s
Δx
characteristic length
m
Δxw
concentration gradient
-
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Appendices
The Appendices include the following:
•
Complete sample calculations with tables of intermediate results.
o Since only the final calculations are included in the body of the report, the
intermediate and sample calculations must be detailed enough for the grader to check
for errors. They must be adequately introduced and explained by text so that the
grader can easily understand them. Equations should be referenced to the Theory
section or literature. Physical and chemical properties used in the calculations should
be referenced to literature.
o Units should always be included and conversions shown.
o The calculations may be neatly handwritten and scanned in.
o You must cite every source from which equations/literature data were drawn.
o NOTE: Even if spreadsheet calculations are attached, you must include
handwritten sample calculations to show how each column/row of the
spreadsheet was obtained. Be sure to define each column and row of the
spreadsheet, as well as the units.
Sample Calculation Rules:
a. Arrange them in a logical order.
b. Define all terms.
c. Show all units/unit balances and conversions.
d. Lead the reader through the work by putting a sentence or two preceding each
calculation explaining what is being done. Work that is easily understood is
more easily graded.
e. Use one set of conditions, wherever possible, to show the logical progression
of the calculations.
f. Any equation used from the Theory section of the lab manual must be cited.
g. Any data or equations from the literature must be cited.
h. Any data table generated by computer calculations must be briefly explained.
i. Numerical values should have the correct number of significant digits (less
than 4) even for the spreadsheet calculations.
•
•
•
•
A scan or screenshot of your original data sheet(s) is to be included as an appendix
(called Raw Data) in your lab report.
o No changes should be made to the original data sheet once the lab session is
complete.
The JSA should be included as an appendix and “called out” in the App/Proc. Section.
Any other pertinent information that does not belong in the body of the report (such as long
derivations or supplemental figures and tables) can be included as an appendix.
Each appendix should have a title (e.g., Appendix A: Sample Calculations) and should start
on a NEW page.
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Lab Report Examples
What follows are two examples you may use when developing your lab report. Note that these
are not perfect examples; their purpose is to provide general guidelines as to the proper
organization and style of a lab report.
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ChBE 4210 – Bioprocess Unit Operations
Lab 2: Transdermal Drug Delivery
Group 8: Fritz Haber, Beatrice Hicks, and *Mae Jemison
Date Performed: September 8, 2023 – Date Submitted: September 22, 2023
ABSTRACT
Diffusion of compounds across the skin plays an important role in the pharmaceutical industry
for drug delivery, but the skin’s properties limit diffusion rate and permeability. The objective of
this experiment was to measure the permeability coefficient and lag time of FITC-Dextran and
Sulforhodamine B across the skin. Two conditions of mice skin, full-thickness and tape-stripped,
were placed in a diffusion cell with the compounds in PBS. The fluorescence of the solutions was
measured using a fluorimeter and correlated to a concentration to determine the extent of diffusion
across the skin. Analysis showed that the permeability coefficient (kp) for the tape-stripped skin
was higher than full-thickness; however, the difference was not significant with 95% confidence.
Additionally, no conclusions could be drawn about the differences in lag time with 90%
confidence, which was likely due to error. A two-factor analysis of variance on kp values showed
that kp differed by 12% between skin conditions but did not differ significantly between the
compounds, indicating the properties of skin are most influential in diffusion. These conclusions
were expected since the stratum corneum of the epidermis is considered the rate-limiting barrier
to diffusion. A source of error included the 3 hr-long exposure of the compounds to light, which
skewed fluorescence readings and therefore gave inaccurate concentration data. Overall, these
results indicate that a transmission method to bypass the outer layer of skin used in a transdermal
drug delivery system would yield the most efficient delivery.
INTRODUCTION
Diffusion of compounds across skin is a technique used primarily in the pharmaceutical
industry for drug delivery but also in toxicology and safety analysis. Skin diffusion is most
commonly applied with transdermal drug patches, such as nicotine or scopolamine, that work by
establishing a concentration gradient between the skin, a semi-permeable adhesive layer, and a
reservoir of gel or liquid which drives the compound down the gradient and into the subject’s
body.2 Transdermal delivery systems are preferable to oral or hypodermic routes because they
bypass the premature metabolization of the drug by the liver, are not painful, and do not produce
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dangerous medical waste. One of the few drawbacks of transdermal delivery is the limited quantity
of drugs that are compatible with this method of administration.3
Properties that affect transdermal delivery include molecule size and skin thickness. The
objective of this experiment was to measure diffusion and permeability coefficients and lag time
of two compounds through the skin. To achieve this objective, FITC-Dextran and Sulforhodamine
B diffusion through skin with and without the stratum corneum was analyzed over time with a
fluorimeter. These data were compared with expected trends based on Fick’s first law of diffusion.
THEORY
The delivery of drugs across the skin is controlled by diffusion kinetics, and its efficacy
depends on properties of the skin itself, such as permeability coefficients. This experiment explores
the relationship between the concentrations on either side of a skin barrier, lag time associated
with diffusion, and the permeability of regular and stripped skin.
Skin is composed of two layers: the epidermis, and the dermis. The dermis is a highly
vascularized layer, while the epidermis is thinner and includes the stratum corneum, a very thin
but densely packed layer of dead skin cells that is considered to be the rate-limiting barrier for
diffusion in processes involving dermal absorption.1 Using both shaved and shaved-and-stripped
skins can elucidate the rate-limiting effects of the stratum corneum and demonstrate how its
removal affects the monitored diffusion.
Although skin is not mechanically uniform throughout, it can be modeled as an isotropic
membrane for simplicity and is governed by Fick’s first law of diffusion shown in Equation 1,4
J = 𝑘𝑘𝑃𝑃 ∆𝐶𝐶𝑉𝑉
(1)
where J is a permeant’s flux, kP is the permeability coefficient, and ΔCv is the permeant
concentration gradient across the skin. These diffusion data can be plotted cumulatively against
time to derive the flux from the slope, which then allows the calculation of the permeability
coefficient for the skin.
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APPARATUS AND PROCEDURE
In this experiment, we used two diffusion cells clamped together on magnetic stir plates to
monitor diffusion of fluorescent compounds across two different types of mouse skin with hair
removed: regular and tape-stripped. PBS was put in one side of the diffusion cell to mimic
biological ionic conditions, while a mixture of FITC-Dextran and Sulforhodamine B was placed
in the other side. Every 30 minutes for 90 minutes, the solution in the PBS side was removed, and
replenished with new PBS. Then the concentrations of diffused fluorescent molecules were
measured by fluorimeter using BLUE and CUSTOM modules to compare these data. The
experimental apparatus is shown in Appendix A.
The experimental procedure was taken from the UO Lab Manual4 and followed without any
deviations. The main safety concern in this experiment was the handling of biological tissue.
Standard safety protocol, including the use of safety glasses, closed-toe shoes, lab coats, and
gloves, was followed.
RESULTS AND DISCUSSION
The objectives of this experiment were to measure the diffusion of certain molecules through
skin and to calculate the lag time and the permeability coefficient, kp. We then sought to verify
these results using statistical analysis. To achieve these goals, we first obtained standard curves
for the two molecules FITC-Dextran and Sulforhodamine B by measuring their fluorescence at
their emission wavelengths, as shown in Appendix D. Since both molecules absorb in the BLUE
fluorometer wavelength, used a CUSTOM wavelength reading to remove Sulforhodamine B and
find FITC-Dextran. A full explanation is shown in Appendix B.
After creating calibration curves, we performed our experiment measuring the diffusion of the
two compounds across full-thickness skin and tape-stripped skin. Figure 1 below shows one such
scenario.
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©2021 School of Chemical & Biomolecular Engineering Georgia Institute of Technology
Figure 1. Cumulative amount of sulforhodamine B
as a function of time for full-thickness skin. Graph slope
shows the flux for each skin.
Figure 1 shows the linear relationship between diffusion of sulforhodamine B and time. These
data sets are assumed to be at a pseudo-steady state, as there is no evidence of a lag time curve.
Figure 2 shows a similar case for the diffusion of sulforhodamine B in the case of tape-stripped
skin.
Figure 2. Cumulative amount of sulforhodamine B as a function
of time for tape-stripped skin. Graph slope shows the flux for each skin.
Figure 2 shows a similar correlation in flux for the tape-stripped skin. However, comparing the
magnitude of the flux, it appears that tape-stripped skin has a higher diffusion rate than fullthickness skin. This result is logical because damaged skin should be more susceptible to
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penetration than normal skin. The high R2 values for each regression justify the linear correlation.
The relationship between skin and FITC-Dextran follows a similar pattern as sulforhodamine B,
and is presented in Appendix E.
To quantitatively analyze the amount of each compound that diffused through the skin, the
permeability coefficient was calculated from the data. This coefficient, kp, gives a direct
relationship between flux and concentration. Averages of kp for each condition are shown in Table
I.
`Table I. kp Values for Various Skin and Compound
Conditions at 95% Confidence
Full-Thickness
Tape-Stripped Skin
Skin
Sh B .0084±.01
.0062±.0069 cm/hr
cm/hr
FITC .0027±.0006
.0031±.0016 cm/hr
cm/hr
The results in Table I imply a greater kp for tape-stripped skin but show no statistical significance
at 95% confidence, likely due to the limited data points collected.
Though lag time was not visible on our flux graphs, we were able to determine lag time as the
x-intercept of each trend line on the graphs. Table II below shows the obtained values for lag time.
Table II. Average Lag Times for Each
Condition at 90% Confidence
Lag Time (min)
FullSkin
thickness
Tape-stripped
Sh B
22±9.17
11.5±12.42
FITCDextran
-23±32.12
-26.5±49.7
Table II shows the lag time for the average data. The negative values for FITC-Dextran indicate
that the pseudo-steady state assumption applied is definitely not valid. The lag time data show no
statistical significance due to limited data.
To further analyze our kp values, we performed an analysis of variance (ANOVA) test to
determine if skin condition and compound influenced each other. The results showed that the
compound-skin interaction was not significant, justifying a two-factor ANOVA test. The results
also showed that the compound used did not have a statistically significant effect on kp. However,
based on ANOVA, there was a significant difference in the skin type on kp. This finding makes
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sense because the presence of damage on the skin should affect diffusion significantly. The full
results are shown in Appendix F.
The largest source of error for this experiment was the limited data points collected, causing
large confidence intervals and statistically invalidating lag times and some kp comparisons.
CONCLUSIONS & RECOMMENDATIONS
The permeability coefficients and lag times for FITC-Dextran and Sulforhodamine B were
successfully measured, and their significance was determined. The kp values for tape-stripped skin
were higher than those of full-thickness; however, there was no significant difference in kp for
both molecules with 95% confidence. Additionally, with 90% confidence, the lag times were not
significantly different and indicated the pseudo-steady-state assumption applied to our data was
invalid. However, an ANOVA on kp values indicated that there was a statistically significant effect
on kp between skins but not between compounds. Thus, the properties of skin are most influential
in diffusion. Therefore, a transmission method such as microneedles to bypass the outer layer of
the skin should be used for the most effective transdermal drug delivery.
We recommend increasing the frequency of readings at the start of diffusion in order to
accurately determine the lag time region. Additionally, we suggest examining the diffusion of
additional molecules structurally different from those analyzed to investigate the role of size and
composition.
REFERENCES
1. Dermal Exposure Assessment: Principles and Applications, 1992. The Risk Assessment
Information System. EPA. http://rais.ornl.gov/ (accessed June 9, 2023).
2. Margetts L., Sawyer R. Transdermal drug delivery: principles and opioid therapy.
CEACCP. 2007, 7(5), 171-176.
3. Prausnitz MR, Langer R. Transdermal drug delivery. Nature biotechnology. 2008, 26(11),
1261-1268.
4. Transdermal Drug Delivery. In Unit Operations Lab Manual; Georgia Tech: Atlanta, GA,
2023; pp 1-14.
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Note: Nomenclature and Appendices followed in the original
report (not reproduced here). See next sample report for examples
of nomenclature and appendices.
40
CHBE 4200 – Unit Operations
Lab 5: Liquid-Liquid Extraction
Group 1: Conrad Aiken, *Flannery O’Connor, and Alice Walker
Date Performed: November 1, 2023 – Date Submitted: November 15, 2023
ABSTRACT
Liquid-liquid extraction (LLE) is important in separations where distillation is not feasible due
to low volatility differences. The objective of this experiment was to determine the effect of plate
oscillation rate on mass transfer efficiency and to evaluate correlations for predicting this effect.
To this end, a Karr reciprocating plate extraction column was used to separate propionic acid from
diesel using water as a solvent. The extract and raffinate were titrated at three different frequencies
(144, 174, and 210 min-1) to obtain the fraction of propionic acid in each stream. The percent of
propionic acid increased as the oscillation rate increased: 71.9% was removed at 144 min-1, while
79.4% was removed at 210 min-1. This increasing trend was due to more surface area for mass
transfer. Using the Kremser equation, the number of equilibrium stages (N) was calculated as 0.569,
0.659, and 0.908 for 144, 174, and 210 min-1, respectively, indicating higher oscillation rates
resulted in a better separation. Based on these N values, the height equivalent to a transfer plate
(HETP) values were calculated as 321 cm for 144 min-1, 174 cm for 278 min-1, and 201 cm for 210
min-1. The trend of decreasing HETP with increasing oscillation rate matched trends found in
literature. However, the experimental HETP values were roughly 50% higher than HETP values
from Bensalem and Tawfik correlations. This discrepancy can be attributed to differences in
compounds in the correlations. Finally, the mass transfer coefficients were found to increase with
increasing oscillation rate. Overall, these results show that to improve mass transfer of propionic
acid from diesel to water, liquid-liquid extraction columns should be run at a high oscillation rate.
INTRODUCTION
Liquid-liquid extraction (LLE) is an important method for separating compounds of similar
volatility and boiling points. It is commonly used in the production of petroleum and organic
solvents. A key benefit of LLE is that no phase change occurs, making it preferable when a
mixture’s components are temperature sensitive. One disadvantage of LLE is that the required
mixing may result in emulsions that harm efficiency.
Physical properties that affect mass transfer efficiency in an LLE column include solvent type
and oscillation rate. The objective of this experiment was to determine how oscillation rate affects
the performance of a Karr reciprocating plate extraction column for separating propionic acid from
diesel using water as a solvent. This objective was achieved by taking flow and composition
41
samples from the raffinate and extract under varying oscillation rates. Titration of each sample
allowed height equivalent to a transfer plate (HETP) to be calculated. These values, along with
height of an overall raffinate transfer unit values, helped determine the relative mass transfer
efficiency for each trial. Finally, experimental trends were compared to predictions from published
correlations.
THEORY
In this experiment, a dilute system with low solubility between the diesel fuel and water exists;
therefore, the operating and equilibrium lines are assumed to be linear. This linearity allows for
continuous contact behavior.
For the operation, a variation of the Kremser equation that operates under the assumption of
linear operating and equilibrium lines can be used to calculate the number of stages:1
 y − yb * 
ln  b
 ya − ya * 
N=
 y − ya 
ln  b*
 yb − ya * 
(1)
where N is the number of equilibrium stages, and the compositions are shown in Figure 1 below.
Figure 1. Extraction column analysis.2
The mass transfer rate between the two fluids is determined by the absorption factor, A:
A=
L
y −y
= b* a*
mV yb − ya
42
(2)
This equation represents a ratio of the slope of the operating line to the slope of the equilibrium
line. If these lines are linear, then the water flow rate, L; diesel flow rate, V; and equilibrium factor,
m, are all considered constant.1
Due to the difference between propionic acid’s solubility in water and diesel, the continuous
contact mass transfer is expressed in terms of an overall mass transfer coefficient, which is based
on the compositions in the raffinate phase and the corresponding height of a transfer unit:
Z = H 0 y N0 y
(3)
where Z is the height of the column, and 𝐻𝐻0𝑦𝑦 is the height of an equivalent raffinate transfer unit.1
This height is described by the following equation:
H0y =
where
V
K ya
(4)
V
represents the height of a transfer unit (HTU).1 Kya is the overall mass transfer
K ya
coefficient, and N0y is found by
N0 y

  yb 
   (A − 1) + 1 
y 
A

=
ln  a


A −1
A




(5)
Substituting Equation 4 into Equation 3 yields1
V
N0 y
K ya
Z=
(6)
Analogous to HTU, height equivalent to a theoretical plate (HETP) can be used to analyze mass
transfer efficiency. A correlation found by Bensalem is used to calculate the height equivalent to a
theoretical plate,
HETP = 24.3(Af )
−0.81
U c 0.21U d −0.7ϕ −0.3
(7)
where A is the amplitude of the reciprocating cycle, f is the reciprocating frequency, Uc and Ud are
the superficial velocities of continuous or dispersed phases, and φ is the holdup of the dispersed
phase in the column.1 A second correlation is from Tawfik, where HETP is described as1
HETP = (Af )
−1.15
[U
43
+ Ud ]
0.235
c
(8)
APPARATUS & PROCEDURE
The experimental apparatus used in this procedure consisted of a 1 in. in diameter by 6 ft long
Karr reciprocating plate extraction column with a variable speed motor, two feed pumps, and two
calibrated flowmeters. A diagram of the apparatus is shown in Figure 2.
Figure 2. LLE apparatus schematic.1
A 250 mL graduated cylinder and burette were used to collect and titrate samples. The procedure
was taken from the Unit Operations Lab Manual1 and performed with the following deviation:
Three oscillation rates were tested rather than four due to time constraints.
Flow rate and composition data were used to determine the HTU and mass transfer
coefficient for each operating condition.
Diesel is combustible, so care was taken to prevent ignition. Additionally, propionic acid
and diesel are both irritants, so direct contact with skin and eyes was avoided.2 Standard safety
protocol, including the use of safety goggles, closed-toe shoes, lab coats, and gloves, was used.
RESULTS & DISCUSSION
To determine how oscillation rate affected the performance of a Karr reciprocating plate
extraction column, we calculated the percent acid removed, the number of required equilibrium
plates, and the mass transfer coefficients. Three oscillation rates (144, 174, and 210 min-1) were
observed, with composition and flow samples from the extract and raffinate taken at each. The
44
samples were titrated with NaOH to determine the propionic acid content. Table I shows the
propionic acid content in each stream.
Table I. Material Balance Closure
Freq
(min-1)
Feed
(g/min)
Extract
(g/min)
Raff
(g/min)
144
0.877
0.141
0.0546
Percent
Acid
Removed
71.9%
174
0.877
0.0162
0.00599
73.0%
210
0.877
0.0557
0.0144
79.4%
As Table I shows, the material balances do not equate, as the amount in should equal the
amount out. Inaccuracies in the flowmeters and difficulties in titrations are likely sources of this
discrepancy. This inequality may also be due to unsteady state operation of the column. Despite
the discrepancy, Table I also indicates that the percent propionic acid removed increased with
increased plate oscillation rate. This trend was caused by higher oscillation rates creating more
surface area for mass transfer to occur.
The number of equilibrium stages, N, for the separation was then determined for each trial.
Titration data were used to find xb, the fraction of the propionic acid in the extract, and ya, the
fraction of the propionic acid in the raffinate (see Appendix A for calculations). Resulting operating
lines were plotted along with equilibrium data as shown in Figure 3 below (Appendix B contains
raw equilibrium data). Diesel typically consists of 65% aliphatic and 35% aromatic compounds3
with molecular weights ranging from 140 to 165 g/mol. Diesel was modeled in ASPEN as a mixture
of 30 wt% heptane, 35 wt% octane, and 35 wt% benzene.
Figure 3. Experimental operating lines for
different oscillation rates and an equilibrium line for
a propionic acid-diesel system.
45
By evaluating the equilibrium lines at each xa and xb values, values for ya* and yb* were
obtained. The number of equilibrium plates (N) was calculated for each trial using a version of
Kremser equation. The resulting N values were 0.569, 0.660, and 0.908 for frequencies of 144, 174,
and 210 min-1, respectively (Appendix C contains calculations). The number of equilibrium stages
increased with the increasing oscillation. This correlation arose because higher oscillation rates
result in a better separation.
The equilibrium number of stages for each trial was then used to obtain values for the
HETP, and these values were compared against HETP values from different correlations (Appendix
D shows these calculations). The HETP values were plotted against oscillation rate as shown in
Figure 4.
Figure 4. HETP values from continuous, Bensalem,
and Tawfik correlation methods.
The HETP decreased with increasing oscillation frequency because the equilibrium number of
stages increased while the column height remained unchanged, resulting in a smaller transfer unit
height. The trends for the Bensalem and Tawfik correlations correspond with theory, yet there is a
large degree of difference between all three methods. This discrepancy could originate because the
correlations were derived for systems that were different than the system used in this experiment.
The heights of an overall raffinate transfer unit, H0y, were then calculated and used to obtain
mass transfer coefficients for each trial. N0y values were calculated and H0y and Kya values were
related using Equation 4 (see Appendix E for these calculations). Figure 5 below shows the
relationship between the mass transfer coefficient and oscillation rate.
46
Figure 5. Mass transfer coefficients plotted against
plate oscillation rate on a log-log scale.
As Figure 5 shows, there is a degree of correlation between the mass transfer coefficient and the
plate oscillation rate, as seen before in other parameters. These results indicate that the mass transfer
coefficient for the separation increases with increasing plate oscillation rate.
CONCLUSIONS & RECOMMENDATIONS
In this experiment, the separation of propionic acid and diesel through liquid-liquid extraction
was successfully characterized. The percentage of propionic acid removed was shown to increase
with increasing plate oscillation rate, despite discrepancies in the mass balance equations. Increases
in the oscillation rates also correlated directly with the number of equilibrium stages. Additionally,
as the oscillation rate increased, the HETP, N0y, and H0y values decreased. Experimental trends
agreed with trends seen in literature correlations, although large discrepancies existed between
experimental and correlated values. Taken together, these observations indicate that larger
oscillation rates in industrial separation processes could result in better mass transfer.
Recommendations for this lab include identifying another literature correlation (such as the
XYZ correlation) that more accurately reflects the experimental conditions.
Additionally,
experimenting with higher oscillation rates and analyzing the costs associated with increased rates
could reveal a point of diminishing returns relative to increased mass transfer.
47
REFERENCES (Should have at least two more refs)
1. Liquid-Liquid Extraction. In Unit Operations Lab Manual; Georgia Tech: Atlanta, GA,
2023; p 1-11.
2. “Chemical Information - Safety Data Sheets” http://www.ehso.com /sds.php,
Environment Safety and Health Online, 2018 (accessed July 1, 2023).
3. Ott, L., & Bruno, T. Variability of Biodiesel Fuel and Comparison to Petroleum-Derived
Diesel Fuel. Energy & Fuels, 2008, 22 (4), 2861-2868.
48
Nomenclature
Symbol
Definition
Units
a
interfacial area
m2
A
amplitude
cm
f
reciprocating frequency
s-1
H0y
height of an overall raffinate transfer unit
-
HETP
height equivalent to a theoretical plate
cm
Ky
mass transfer unit
-
L
extract flow rate
m3/s
m
equilibrium factor
-
N
number of trays
-
Uc
superficial velocity of continuous phase
cm/s
Ud
superficial velocity of dispersed phase
cm/s
V
raffinate flow rate
m3/s
xi
concentration
kg/m3
ya
propionic acid concentration in feed
-
ya *
equilibrium propionic acid concentration in feed
-
yb
propionic acid concentration in raffinate
-
yb
equilibrium propionic acid concentration in raffinate
-
yi
concentration
kg/m3
Z
height of column
cm
𝜑𝜑
holdup of the dispersed phase in the column
*
49
Appendix A. Experimental Data and Calculations
Table AI. Feed Properties
Trial 1
Trial 2
Trial 3
Average
Standard
Deviation
M (g)
3.975
4.0098
3.989
-
-
V (mL)
5
5
5
-
-
Ρ (g/mL)
0.795
0.80196
0.7978
0.79825
0.00350
Sample Calculation for mol of NaOH
=
mol NaOH
mL of NaOH × [ NaOH ] 5.5mL × 0.02
= = 0.000110
1000
1000
(A1)
Sample Calculation for propionic acid concentration
=
[ Acid ]
mol of acid
0.000110mol
mol
= = 0.000011
mL of sample
10
mL
(A2)
Sample Calculation for propionic acid mass flow rate
mass of acid= [ Acid ] ⋅ flow
=
rate 0.000011
Sample Calculation for volume of propionic acid
mol 1.165mL 74.1g
⋅
⋅ = 0.000949 g / s
mL
sec
mol
(A3)
volume of acid = [ Acid ] ⋅ volume×molecular weight×density =
0.000011
mol
74.1g 99 g
⋅100mL ⋅
÷
=
0.0823mL
mL
mol
mL
(A4)
Sample Calculation for volume of diesel
volume of diesel = total volume - volume of acid = 100mL - 0.0823mL = 99.9 mL
(A5)
Sample Calculation for mass flow rate of diesel
volume of diesel
99.9 mL 0.798 g
⋅ density of feed =

time of sample
94sec
mL
(A6)
Sample Calculation for YA
=
YA
mass of acid
0.000949 g / s
=
=
0.00111
mass of diesel
0.849 g / s
50
(A7)
Oscillation #1 – 144 oscillations/minute – 0.7cm amplitude
Trial
1
2
3
Average
Standard
Deviation
Trial
1
2
3
Average
Standard
Deviation
Table AII. Raffinate flow properties for Oscillation #1
Raffinate
Volume (mL)
Time (seconds)
Flow rate (mL/sec)
100
94
1.064
100
75
1.333
100
91
1.099
1.165
0.147
Table AIII. Extract flow properties for Oscillation #1
Extract
Volume (mL)
Time (seconds)
Flow rate (mL/sec)
100
73
1.370
100
70
1.429
100
70
1.429
1.409
0.0339
Titration – Raffinate
Trial
1
2
3
Table AIV. Titration raffinate properties for Oscillation #1
Volume
Volume NaOH
mol NaOH
mol propionic
Raffinate (mL)
(mL)
acid
10
10
10
5.5
5.2
5.1
0.000110
0.000104
0.000102
0.000110
0.000104
0.000102
Propionic acid
concentration
(mol/mL)
0.000011
0.0000104
0.0000102
Table AV. Titration raffinate properties for Oscillation #1 continued
mass Acid (g/s)
0.000949
0.000898
0.000881
Average
0.0546 g/min
Standard
Deviation
0.00216 g/min
Vacid (mL)
0.0823
0.0778
0.0763
Vdiesel (mL)
99.9
99.9
99.9
-
-
-
-
mass Diesel (g/s)
0.849
1.06
0.877
Average
55.8 g/min
Standard
Deviation
7.01 g/min
(More appendices followed in the original report…)
51
YA
0.00112
0.000844
0.00101
Average
0.000989
Standard
Deviation
0.000138
ya*
0
0
0
Average
0
Standard
Deviation
0
Appendix A: Scientific Writing & Format Specs
The “Grammar” of Scientific Writing & Format Specifics of the ChBE Lab
Report
Every field has its own “language”—that is, its own specific, standardized, conventional
ways of using language and formatting text. One could call this the “grammar of a profession”
or the discourse conventions of a community. This section outlines aspects of the “grammar” of
chemical engineering that are significant to lab report writing.
1. Verb Tense:
Past Tense: In your lab report, things that occurred in the past should be written about in the
past tense.
• In the experiment, the objectives were already achieved, so objectives will also be
in the past tense,
• Additionally, data collection and analysis occurred in the past. Any trends that
occurred (e.g., retentate purity increased with feed pressure) also occurred in the
past. There are two exceptions:
Present Tense: In your lab report, things that are still true in the present (as I am reading
your report) and unaffected by time should be written about in the present tense.
a. Use the present tense when writing about current facts or events
(industrial applications or advantages and limitations of a process, for
example).
This use of the present tense will occur mainly in the first paragraph of the
Introduction, and at the beginning of the Abstract (although there could be
other uses also)
b. Use the present tense when writing about things that are eternally in the
present, things that are unaffected by time (equations, figures, tables, and
theoretical ideas). Equation 9 always “yields”; Figure 3 always “shows;”
The model (or the theory) always “predicts.” To clarify: if you used the past
tense in these situations, you would be suggesting that something different
holds true now: “Equation 9 yielded Equation 10 (at one time), but now
Equation 9 yields something else (because of new research, theory, etc.).”
This rule applies mainly in the Theory section, but it will also come into
play in the Results and Discussion section when you are explaining your
graphs and tables.
(e.g., “Figure 3 shows that when time increased, temperature decreased.” NOTE: the verb
tied to the “thing” in the perpetual present is in the present tense (“shows”), but the verbs that
relate to the actual experiment are in the past tense (“increased” and “decreased”)).
52
2. Passive vs. Active Voice:
Passive voice tends to make your writing vague and wordy, so you should try to avoid it in
all types of writing. However, passive constructions are appropriate in certain situations in
scientific writing.
NOTE: Passive voice, passive verbs, or passive constructions occur when there is no agent
in the sentence—that is, there is no one or thing doing the action (EX. “An award was given
to Dr. Galfond.” This is passive voice because the sentence doesn’t indicate WHO or
WHAT “gave the award.”).
a. Passive voice is appropriate when it doesn’t matter who performed the action (or you
purposefully want to obscure who did what).
Ex.
The pressure was measured at three different flow rates.
[someone in the laboratory did this, but it doesn’t matter who].
b. Passive voice is appropriate when you want to avoid a string of sentences all
beginning with “I” or “we.”
Ex.
To begin, we determined the porosity and mean diameter of the sand used
in the packed bed. The porosity of the packed bed was calculated by both
weight and volume. To determine εm by weight, a tared 359 ml graduated
cylinder was filled with approximately 700 g of sand two times. The mass
of sand was measured and then the graduated cylinder was filled with
water until the water level reached the top of the sand level.
[The author and his or her lab partners did all of these things, but
an agent-action style would focus too much on the author AND
would become too repetitive: We determined, we calculated, we
filled, we measured, etc.]
c. Passive voice is appropriate when you are telling the “story” of the object you studied
or the apparatus you designed.
Ex. The packed column used in the experiment was a xxx by xxx cm transparent
Plexiglas column packed approximately 7 7/16 cm with sand. A U-tube
manometer was connected to the packed bed with one pressure reading
below the bed and another reading below the top weir. Tubes, connected
at the bottom of the bed, allowed for static pressure to be measured
separately from the pressure drop. The tube connected to the bottom of
the bed was raised to meet the top tube, thereby negating the head of water
in the column available for measurement by the manometer.
[this is the “story” of the fluidized bed apparatus]
53
3. Although you don’t want to overdo it, you may use the 1st person plural (“we”) in your lab
reports but only in certain situations (you’ll only use “we,” not “I”, since your lab is a group
project).
a. You may use “we” to refer to work that you and your lab group did.
Ex.
We turned on the two cold water valves.
We used the XYZ correlation to verify the experimental results.
We recommend that the department purchase a new pump.
We found substantial agreement with the literature values.
DO NOT USE “WE” to refer to you and your reader or you and other unspecified members of the profession (ex. “In the field of chemical engineering, we
use pumps in a variety of situations.”)
You will find “we” is most appropriate in the Apparatus and Procedure section,
possibly Results & Discussion, and the Conclusions and Recommendations
section. If you’re using “we” in the Theory section, you’re probably using it
inappropriately—in the general, vague way, rather than the specific way.
4. Formatting and punctuating equations in the Theory section can be a little confusing.
Please follow the guidelines below, which are based on the ACS Style Guide.
a. Each equation should appear on its own line, separate from the prose text.
For better readability, equations should be centered on the page.
EX.
Combining Equation 4 with Equation 5 yields
X+Y+Z=A
(6)
b. Each equation should be numbered. Numbers should be sequential and
flush with the right-hand margin.
EX.
Combining Equation 4 with Equation 5 yields
X+Y+Z=A
(6)
c. Generally, treat the equation as if it were a regular noun and punctuate
accordingly. However, you should NOT include punctuation at the end of the
equation. According to the ACS Style Guide, “Punctuation that would
normally be present at the end of an equation in text is absent but implicit at
the end of a displayed equation.” Thus, even if the end of the equation is also
the end of the sentence, you should NOT put a period at the end of the
54
equation. Your reader will figure out that the sentence has ended just from the
context.
I. Your sentence is
Combining Equation 4 with Equation 5 yields
X+Y+Z=A
(6)
[There is no punctuation between the verb and the equation—because the equation
functions as the direct object of the verb. (Imagine substituting the words “an elephant”
for the equation, X+Y+Z=A. Would you put a comma or colon between “yields” and “an
elephant”? No. Therefore, there is no punctuation between “yields” and the equation.)]
ii. Your sentence is
Combining Equation 4 with Equation 5 yields
X+Y+Z=A
(6)
where X is salt, Y is pepper, and Z is sugar.
[Again, there is no punctuation between the verb and the equation. However, the
sentence does not end after the equation in this instance but continues on with a
dependent clause. This dependent clause is part of the same sentence, so make sure that
the first word in the clause (here, it’s “where”) is lowercase.]
iii. Your sentence is
Combining Equation 4 with Equation 5 yields Equation 6:
X+Y+Z=A
(6)
[The stuff before the equation stands as a complete sentence. If the equation weren’t
there, you would simply put a period. However, since the sentence continues, you need a
colon after “Equation 6.”]
FYI: The colon, as a form of punctuation, is used
after an independent clause (a complete sentence) to
indicate a “pause-stop” before a word or list that
illustrates or explains something in the first clause.
55
iv. Your sentence is
Combining Equation 4 with Equation 5 yields Equation 6,
X+Y+Z=A
(6)
where X is salt, Y is pepper, and Z is sugar.
[In Example iv., the “where” clause after the equation is a continuation of the sentence
(because the “where” clause modifies “Equation 6”). Therefore, you need to put a comma
after “Equation 6,” instead of a colon.]
v. Your sentence is
Equation 5 can be simplified to yield Equation 6,
X+Y+Z=A
(6)
where X is salt, Y is pepper, and Z is sugar.
[This is a little trickier to understand. Think of it this way: What follows the comma—
“X+Y+Z=A”—is an appositive, which means it is exactly the same as the term or phrase
that comes directly before it—in this case, “Equation 6.” This is kind of like “By using
Ginkoba, the greatest memory supplement ever, it is possible to regain your ability to
remember things.” The rule is that appositives are both preceded and followed by
commas, but as explained earlier, we do not punctuate at the end of equations that are set
off from the text.]
vi. Your sentence is:
This relationship is shown by the following equation:
X+Y+Z=A
(6)
where X is salt, Y is pepper, and Z is sugar.
[This is a variation on Example v. The difference is that the equation X+Y+Z=A is not
EXACTLY the same as what came before it—thus, it is not an appositive. Instead, it is
the beginning of a new clause that needs to be connected to the preceding independent
clause by a colon.]
A note on equation editor:
Formulas and equations should look professional. Therefore, a good equation editor
should be used to make these equations readable instead of piecing together bits of text.
Microsoft Word has its own equation editor under “Insert Object,” and third-party
56
products such as MathType can be used with MS Word or other word processors. Use of
a proper equation editor will produce results such as
 14 x 
α = lim 2.3 
(3)
n →0 n


as opposed to
alpha=the limit as n approaches zero of (14x/n 2.3).
(3)
Symbols, superscripts, subscripts, and equation editors can also be used to make
mathematical terms used in the text look professional. For example, terms such as y3, 3.4
± 0.1, Å, and v should be used instead of y^3, 3.4+/-0.1, angstroms, and v-dot.
5. Figures and tables also have special formatting rules. Neither should be simply “dropped”
into the text (you must introduce them and then explain them), and both must be properly
oriented on the page.
For more specific rules for figures and tables, please see Appendix E.
6. In referring to specific equations, tables, or figures by number, the words “Equation 1,”
“Table II,” or “Figure 3” should be initial capitalized, as they are now proper nouns
(So . . . Equation 1, NOT equation 1). It’s also better to refer to figures as “figures,” not
“graphs.”
7. All measurements should include units; SI is preferable where possible. Although you
should abbreviate units, DO NOT USE PERIODS AFTER THE ABBREVIATION.
(Exception: Use “in.” to indicate inches (since “in” is an actual word, it can create
confusion if you don’t include the period after it.)
You should typically leave a space between a number and its associated unit (e.g., The
column was 20 cm in length) with the exception of ° (the degree symbol) and % (the percent
symbol), where there should be no space between the number and the unit (e.g., We ran the
experiment at 30°C and obtained 25% fructose conversion.)
8.
Formulas as well as figures and tables should use the appropriate scientific notation
rather than the exponential notation typical of computer output. For example, 2.67×10-3
should always be used instead of 2.67E-3 (the × symbol can be inserted by using the Insert
Symbol command in WORD, and the superscript is available by highlighting the text and
hitting CTRL-D and selecting “Superscript”). Computer notation may be appropriate for
large amounts of numbers in a spreadsheet located in an appendix, but not in the main report
text or any tables or figures contained therein.
9.
There is no standard citation style for the field of chemical engineering. Indeed, citation
styles vary from publication to publication. However, all publications do two things in
common: 1) they keep track of cited sources by referencing the source within the text; and 2)
they give full bibliographic information in a section entitled “References.” These two things
57
complement each other: the in-text citation is short so as to not clutter up the prose, while the
reference section fills out the in-text information so that the citation can be located if needed.
For the purposes of our course, we will be using the formats as presented in the Reference
section above and the In-Text Citations section below (both adapted from the ACS Style
Guide) to do these two things.
58
Appendix B: In-Text Citations
To keep track of cited sources within the text, use superscript numbers at the end of the
sentence (after the final punctuation) in which the reference is made. Occasionally, you
may place the in-text citation within the sentence (not at the end) if you feel that placing
the citation at the end of the sentence would be misleading.
EX. Readable writing expresses actions as verbs.1
Rules for citations:
•
Start with 1 and number consecutively throughout the paper, including references in
text and those in tables, figures, and other non-text components. These numbers
correspond with your numbered list of references (see section on References in Style
Guide). You may wish to use EndNote or a similar reference management
program for references and citations.
•
If a reference is repeated, do not give it a new number; instead, use the original
reference number.
•
Figures taken from an outside source or from the lab manual should be cited at the
end of the caption.
A complication: In the Theory section, superscript citations still appear at the end of the
sentence. However, we do not put the citation on the same line as an equation. Instead,
you may place the citation either:
•
at the end of phrase or clause that is directly before the equation, or
•
at the end of the clause that sometimes follows the equation.
Examples:
Combining Equation 4 with Equation 5 yields Equation 6:1
OR
X+Y+Z=A
(6)
Combining Equation 4 with Equation 5 yields
X+Y+Z=A
where X is peanuts, Y is popcorn, and Z is pretzels.1
59
(6)
Appendix C: Writing - Style & Grammar
Better Sentences and Paragraphs
You are doing many things when you are revising: working on transitions so as to reveal the
relationships between things, re-organizing for more logical presentation of information, and
reworking sentences and paragraphs for clarity and effectiveness. This section offers some tips
for how to go about reworking your writing at the paragraph and sentence level.
1. Keep down word length. Don’t use a longer word when a shorter one will do just as well.
Utilize
Terminate
Substantiate
>>>Use
>>>End
>>>Prove
2. Keep down sentence length: Aim for 15-20 words on average, although occasional longer
and shorter sentences are nice to break up the monotony.
3. Keep down paragraph length. Each paragraph should have ONE main idea. Usually, once
a paragraph reaches 1/3 of a page in length, it should be split (in a logical place) into two
paragraphs.
4. Eliminate needless words.
all of the labs
used for fuel purposes
uniformly homogenous
during the course of
it is important to note that
>>>all labs
>>>used for fuel
>>>homogenous
>>>during
>>>> (delete it!)
5. Simplify positive/negative constructions.
were not a success
or
did not succeed
>>> failed
did not pay attention to
>>> ignored
6. Watch out for the “it/this…that” and “there are…” syndrome. Activate verb and shorten
statements.
“This is a subject that interests many
chemical engineers.”
>>>“This subject interests many
chemical engineers.”
“There are two factors contributing to
>>>“Two factors contribute to this
60
this observation.”
observation.”
7. Eliminate affected language.
utilize
ascertain
contiguous
>>>use
>>>find out
>>>touching
8. Eliminate empty, wordy phrases.
due to the fact that
the fact that we did not succeed
during the course of
for the reason that
>>>because, since
>>>our failure
>>>during
>>>because
9. Express coordinate ideas in parallel form. “Parallel form” means that the two ideas should
be the same part of speech – so both adverbs, both verb phrases, both clauses, etc.
The overall heat transfer coefficient can be
found two ways, theoretically or by experimental
runs of the system.
(Problem: “theoretically” is an adverb, while
“by experimental runs…” is a prepositional
phrase.)
>>>The overall heat transfer coefficient can
be found two ways, theoretically or
experimentally.
Or: … by theoretical calculations or by
experimental runs of the system.
10. Express crucial action as verbs, not as nouns.
The data are proof of the thesis.
There is literature agreement.
Vaporization of liquid streams occurs
at the mixture’s boiling point.
>>>The data prove the thesis.
>>>The data agree with literature values.
>>>The liquid streams vaporize at the
mixture’s boiling point.
11. Put the doer close to what’s being done. (In other words, put subject close to verb.)
The twins, after stubbornly going to the
same high school despite the advice of
their parents and teachers, chose different
colleges.
>>>The twins chose different colleges
after stubbornly going to the same high
school despite the advice of their parents
and teachers.
12. Put descriptions (or modifiers) close to what they describe.
The pasture contained several cows seen by >>>Reporters saw a pasture containing several cows
news reporters that were dead, diseased, or dying. that were dead, diseased, or dying.
61
Appendix D: Other Standard Writing Conventions
Correctness is important in any form of writing. You should own a grammar handbook so
that you can look up rules and figure out how to correct mistakes that are marked on your graded
reports (Diana Hacker’s A Writer’s Reference is a good one, as is Sally Barr Ebest’s Writing from
A to Z). I also recommend the Purdue Online Writing Lab (OWL) for more detailed
explanations of some of the guidelines here. Although you are ultimately responsible for
catching and correcting all errors, the list offers a place to begin your editing, as it represents a
quick overview of common problems.
1. Spelling
Use your spelling and grammar checker. In addition, look up words in a dictionary if you
are unsure of their meaning or spelling. As a final step, proofread to make sure spellcheck
didn’t miss anything (it often does—plus, the spellchecker won’t notice if you write
“form” rather than “from”).
2. Wrong Word Usage
Be aware of the differences between commonly confused words (e.g., it's = it is. its =
possessive; too/to; their/there; weather/ whether; verses/versus; then/than, led/lead, etc.).
3. Word Choice
Be careful to say what you mean, especially where homonyms (words that sound alike
but are spelled differently) are concerned. Don't confuse pairings like except/accept;
effect/affect, and so on. (“Effect” is usually a noun—“My teacher had a great effect on
me.”—whereas “Affect” is usually a verb—“The increase in water flow rate did not
affect the pressure drop.”)
4. Fragments
All sentences must be complete sentences. That is, they must contain both a subject and
a verb. Be especially careful to avoid fragments beginning with words like although,
because, especially, when, where, and since. (You may, of course, start sentences with
these words, but you just have to be careful that you’ve written a complete sentence.)
Example of fragment: Although our results appeared to agree with theory.
Correct: Although our results appeared to agree with theory, they were not
statistically significant.
5. Noun-Pronoun and Noun-Verb Agreement
All singular nouns take singular pronouns. Plural nouns take plural pronouns. Likewise,
all singular nouns take singular verbs, and plural nouns take plural verbs. Remember to
use the appropriate verb for the sentence's subject (which isn't always the same as the
noun that immediately precedes a given verb).
Ex: The pilot as well as all of her passengers was rescued. (Pilot ... was, not
passengers were.)
*Remember that the word “data” is plural and requires a plural verb (i.e., “these
data were...,” not “this data was...”).
62
6. Clear References
Make sure all of your pronouns refer clearly to a noun that precedes them. Pronouns
should not refer vaguely to an entire sentence or to a clause.
When possible, avoid using “This” alone—try instead to say “this result” (or this
behavior, trend, agreement, etc.). When using “it,” be sure that the antecedent (the word
that “it” points back to) is clear.
Ex: Some people worry about wakefulness but actually need little sleep. This is
one reason they have so much trouble sleeping. [Here, “This” could refer to the worry
OR to the need for little sleep OR to psychological problems or something else that hasn't
even been mentioned.]
7. Comma Usage
Commas should be used in the following situations:
a. To separate independent clauses joined by a coordinating conjunction.
Ex: The water was stirred thoroughly, and the temperature of the water was
recorded. (Note that both clauses on either side of the “and” can stand alone as
complete sentences—therefore they are independent clauses, and you need a comma)
b. After an introductory word, phrase, or clause.
Ex: Once the speed was set, the flow rate was adjusted.
(Here, the subject of the sentence is “the flow rate.” The part of the sentence
preceding the subject cannot stand alone as a complete sentence; therefore, we put a
comma between that clause and the main clause (which starts with the subject.)
Ex: Because the first trial yielded unreasonable data, we analyzed only the second
and third trials.
(Here, the subject of the sentence is “we.” See the previous example for more
explanation.)
c. When you are listing more than two items.
Ex. We calculated TDH, BHP, and efficiency. (Note the comma before the
“and”—this is called the “serial comma” or the “Oxford comma” and it is
required in most technical publications, including your lab reports!)
d. To set off non-restrictive elements (clauses or phrases).
A non-restrictive element is one that would not drastically alter the core meaning
of the sentence if the element were removed.
Ex. Our results showed a linear relationship between conversion and temperature,
indicating that the enzyme was more active at higher temperatures.
(The underlined portion is a non-restrictive participial phrase…if removed, the
core meaning of the sentence would still be clear.)
Do not use commas to separate two compound elements, such as verbs, subjects,
complements, or predicates.
63
Ex: We stirred the water thoroughly and then recorded its temperature. [no
comma!] (Note that although the first clause is independent, the second one—“then
recorded its temperature”—is not because it cannot stand alone as a sentence.
Therefore, no comma is required.)
8. Comma Splices
These are also known as run-on sentences or fused sentences. Here, you “splice” two
sentences together with nothing more than a comma. Comma splices are grammatically
incorrect.
(Note: these almost always occur near a conjunctive adverb such as therefore, thus, or
however.)
Example of a comma splice: The first trial produced unreliable data, therefore, we ran
the experiment again.
To correct: turn one sentence into a dependent clause, join the sentences with a semicolon, or break them up into two or more sentences
Correct: The first trial produced unreliable data; therefore, we ran the experiment again.
9. Colloquial Speech
Avoid using slang, clichés, or very informal language in formal lab reports.
10. Colons and Semicolons
These useful punctuation marks are often used incorrectly. Note – they are not
interchangeable!
Semicolons (;) join closely related independent clauses (two complete sentences):
EX. 1. In the fixed bed experiment, pressure drop increased linearly with
superficial velocity; however, once the bed was fluidized, pressure drop remained
relatively constant.
Semi-colons may also be used to separate lengthy items (one or more of which has
internal commas) in a series.
EX. 2. The objectives were to determine productivity and reaction rate; model the
relationship between flow rate, temperature, and conversion; and analyze the
economic feasibility of the process.
Colons (:) introduce explanations or examples, or they may introduce a series, a list, or a
quotation. Colons are used only after an independent clause; however, what comes
AFTER the colon may or may not be an independent clause.
• EX 1. Our poor data can be explained by an experimental error: we forgot to
check the pH levels of the broth.
• EX 2. A chocolate cake has several key ingredients: flour, sugar, butter, eggs,
milk, cocoa, and baking powder.
64
11. Possessives and Plurals
Be careful of the distinction between possessives and plurals. Plurals refer to more than
one of a thing; the possessive case (which requires an apostrophe) designates ownership.
Possessive: The girl’s eyes were brown.
Plural: The girls had brown eyes.
Plural AND Possessive: The girls’ eyes were brown.
12. Abbreviations
With the exception of units, do not use abbreviations (e.g., use “versus” NOT “vs.”) in
the main text. You may, however, use abbreviations inside parenthetical statements or in
figure captions and table titles.
Ex: At the store, we bought fruit, for example, apples, oranges, bananas, and so
on.
But: At the store, we bought fruit (e.g., apples, oranges, bananas, etc.).
13. Numbers
o Numbers less than 10 should be spelled out; numbers 10 and greater should be written
as numerals (e.g., The experiment used 30 flasks. We then poured the contents of the
flasks into two tanks.)
o However, any number associated with a unit should be written as a numeral,
regardless of how large the number is (e.g., We ran the pump at 5 RPM.).
o Put a space between the numeral and the unit, except with ° and %, where there is
no space between the numeral and the unit.
o Use all numerals in a series or range containing numbers 10 or greater (e.g., Either 5,
8, or 12 experiments were run.).
o When a sentence starts with a specific quantity, spell out the number as well as the
unit of measure (e.g., Fifteen milliliters of supernatant were added to the vessel.) If
possible, however, rework the sentence to avoid.
14. “A lot” is two words.
15. “Cannot” is one word.
16. The word “data” is plural. So, “The data show,” “The data indicate,” “These data are,”
and so forth.
17. Do not use contractions (e.g., can’t, won’t, etc.) in lab reports.
18. Avoid gendered prose. Make pronouns plural when possible; when not, use “he or she”
or “him or her,” and so on.
19. “Respectively”
In general, you should try to avoid constructing sentences that require the word “respectively”
to be tacked on at the end. It is harder to read a sentence that says “Water contents were 92,
65
128, and 280 g kg-1 for samples 5, 6, and 18, respectively” than the more straightforward
version: “Water contents were 92 g kg-1 for sample 5, 128 g kg-1 for sample 6, and 280 g
kg-1 for sample 18.” Yes, the second version is a bit longer, but it is also a lot clearer and
easier to read. You might also consider presenting these data in a table instead.
Occasionally, it’s okay to use “respectively” when you are listing two or more values of a
similar type, for example, “The overall heat-transfer coefficients for the plate-and-frame
exchanger at x, y, and z conditions were a, b, and c, respectively” (note that there is always
a comma before “respectively”).
However, it’s NOT okay to use “respectively” when comparing apples and oranges. For
example, you would not say “Mary’s hair color, height, and IQ are brown, 5’5”, and 130,
respectively.” Likewise, when you are trying to convey different types of values (often with
different units) in your lab report, don’t use a structure that requires the use of “respectively.”
It is clearer to say “Mary’s hair color is brown, her height is 5’5”, and her IQ is 130.”
20. Hyphenation (borrowed, with a few small changes, from “A Short Guide to Technical
Writing” written by the Faculty of the School of Chemical Engineering at the University of
Utah)
Because of the importance of the hyphen, especially in scientific and technical writing, the
discussion of this most misused of all marks of punctuation is necessary. The importance of this
small mark cannot be exaggerated. Its presence or absence can change a meaning completely.
Was the tank recovered or re-covered? Is it a light gas unit or a light-gas unit? Static liquid-seal
height or static-liquid seal height? The student must decide whether each adjective can modify
the noun independently or whether two or more, as a one-word compound modifier, are needed.
Consider "heat transfer data"; are they heat data or transfer data, or does it take both words as a
unit to express the idea accurately? If so, hyphenate. In the expression "double pipe heat
exchanger," is it a pipe exchanger or a double exchanger? Since neither makes sense, “double”
and “pipe” are operating as a compound modifier; therefore, use a hyphen.
As you can see, inability to understand the function of the hyphen and its correct
application is one of the factors which may defeat the very purpose of one’s research. The failure
of our first $16 million Venus rocket was due to the omission of one little hyphen from the
computer data. It is therefore vital, for purposes of clarity and precision, that the writer
familiarize him/herself with the conventions of hyphenation. Although the rules are somewhat
fluid and in a constant state of flux, some well-established standards nevertheless exist, the
rudiments of which are detailed below. Should a more complete list be desired, consult the rules
on hyphenation in Webster's New Collegiate Dictionary or another reliable source.
1. First and foremost is the rule that, when two or more words modify another word as a unit,
the hyphen must be used to show the compound relationship. In the examples below, chosen
because they are among the most commonly used expressions in chemical engineering, observe
that, without the hyphen, the precise meanings of the modified nouns would be seriously in
doubt. The ordinary reader might not be able to detect the real meanings at all, and even the
66
technician might be puzzled. The writer owes the reader the courtesy of making his/her meaning
unmistakably clear, and a properly placed hyphen is one way of doing so.
acetic-acid water system
bubble-cap tray
bulk-air temperature
chemical-process equipment
constant-head tank
constant-pressure theory
continuous stirred-tank reactor
composition linear diagram
dissolved-oxygen concentration
dynamic-process-control analysis
enthalpy-difference driving force
exit-line pressure
fluid-column height
transport coefficient
fluid-friction factor
laminar-velocity profile
low-energy bond
inside-pipe cross-sectional area
liquid-gas interface
gas-bubble column
heat-exchange-product stream
heat-transfer-film coefficient
impact-velocity feed line
liquid-temperature air-enthalpy plot
logarithmic-mean temperature
constant-pressure enthalpy
proportional-plus-integral-mode
reciprocal-film heat-transfer equation
scintillation-counter spectrometer
sensible-heat transfer
steam-jacketed one-tube-pass heat
thermal-energy transfer
time-drying-rate plots
tray-type column
tube-flow viscometer
water-head pressure
Exception: In scientific writing, the compounds “mass transfer” and “steady state” do not
need to be hyphenated when functioning as two-word modifiers (e.g., “steady state behavior,”
not “steady-state behavior”).
2. In a series of hyphenated words having a common base, use suspended (or “hanging”)
hyphens:
a two- or three-year study
dextro- and levo-tartaric acid
low-, medium-, and high-density polyethylenes
T- and H-shaped rib design
3. Although there are exceptions, a compound modifier is not hyphenated when it stands
after the noun or in the predicate:
a built-in oscillator
an oscillator is built in
a T-shaped metal support
the support is T shaped
a day-old solution
a solution a day old
67
4. Do not hyphenate with “-ly” adverbs:
an imperfectly rounded Styrofoam ball
accurately held dimensions
5. If the preceding adjective is in the comparative or the superlative degree, no hyphen is
used:
a high-priced unit but a higher priced unit
6. Prefixes are usually written solid with the word modified, except when an awkward
doubling or tripling of letter occurs or when the word modified is a proper noun:
coexist hydroelectric millivolt
countercurrent infrared nontechnical
but
co-orbits non-Newtonian shell-like
inter-Allied photo-optical trans-Stilbene
intra-atomic pre-exposure
However, "coordinate" and "cooperate" need not be hyphenated.
7. Since a different meaning may be conveyed by writing a prefix solid with the word, a
hyphen may sometimes have to be used.
resort to other means
recover the effluent
recollect past errors
microin (correct)
reform the methods
unionized labor
re-sort the particles
re-cover the receptacle
but re-collect the filtrate
micro-in. (better)
re-form the molecules
un-ionized atoms
8. Words compounded with ex- (former), self-, and quasi- are hyphenated.
ex-chairman self-evident quasi-scientific
9. Various parts of speech are often compounded when no one word will accurately depict
the idea.
When used as the parts of speech designated below, they are hyphenated.
air-dry (v.)
heat-treat (v.)
stand-in (n. or adj.)
by-product (n.)
start-up (n.)
down-drag (n.)
mix-up (n.)
straight-line (adj.)
follow-up (n.)
power-driven (adj.) water-free (adj.)
68
foot-pound (n.)
right-hand (adj.)
well-founded (adj.)
half-hour (adj.)
short-circuit (v.)
well-known (adj.)
Example: The initial experiments require follow-up. But, we follow up our experiments with data
analysis.
10. Through frequent use, certain compounds lose the hyphen and are written solid. Others
drop the hyphen but are still written as two words. The dictionary is the criterion, but if
the words are too new to appear there, common convention must be the guide.
acidproof
downdraft
nonnuclear
shakedown
airline
downstream overall
sheetmetal
airstream
downtime
oversized
shutdown
airtight
drawoff
overhead
standpipe
all right
fallout
output
blowdown (n.)
blowout (n.) flow rate
payoff (n.)
streamline
breakdown (n.) free fall
payout (n.)
throughput
buildup
halfway
percent
turbojet
bypass
heat exchanger phototype
twofold
byproduct
holdup
photosensitive upend
checkup (n.) input
pinpoint
upkeep
crosscut
intake
pipeline
upstroke
crossflow
layout (n.)
radioactive
voltmeter
cross section lineup (n.)
setscrew
wavelength
dew point
makeup
setup (n.)
widespread
downcomer mass transfer set point
worthwhile
11. For clearer and smoother reading, it is often advisable to avoid excessive or awkward
hyphenation by writing the expression in a different way. However, if the writer prefers the
long compound modifier before the noun, the hyphens must be used.
"A four-foot-deep seven-by-five-foot tank" is better written "a tank four feet deep and seven by
five feet wide."
"Corrosion-, heat-, and cold-resistant material" or "material resistant to corrosion, heat, and
cold."
69
Appendix E: Tables and Figures
The format requirements for figures and tables vary widely among technical publications.
However, the format presented here is consistent with most technical publications in the science
and engineering field and should be followed for all lab reports.
Remember that you are limited to no more than FOUR (4) tables and figures total in the
Results & Discussion section. You may also use tables and figures in other sections, such as the
Theory or Apparatus & Procedure sections, as needed (but don’t go overboard).
Tables
Specific rules for Tables:
•
They should be centered on the page and they are numbered using Roman numerals.
•
The number and title should be centered above the table.
•
Table titles should:
o Use 10-point font.
o Use Title Case by capitalizing the first letter of important words (generally,
words longer than 4 letters).
o Be single-spaced.
•
Do not bold the entire table title. It’s okay to bold the title number (e.g., Table I), but
bolding the entire title is not necessary and can be distracting.
•
Define the units of each term.
•
Do not just cut and paste Excel excerpts into your report! You need to make an
actual table in Word and then copy/paste in each line of Excel data that you want.
o Be sure to convert Excel data to Times New Roman 11 or 12 font (note – it’s
okay to use 10 pt. for the table data if necessary to fit the table in the column)
o Don’t use the Excel style of formatting (e.g., 5.54E-04) in the main body
of the report. Use scientific notation instead—so, 5.54*10-4 (Note: in
appendices, it’s okay to use the Excel style)
70
Any additional explanatory notes should be listed in the table or below the table, as illustrated in
Table I.
Table I. Enhancement of Convective Heat Transfer Coefficient (h)
from Various Pipe Coatings
h (free convection)
h (forced convection h (forced convection Coating Material
W/(m3 K)
laminar regime)
turbulent regime)
W/(m3 K)a
W/(m3 K)b
Copper plating
13.45
16.21
17.62
Polyester
11.55
16.97
19.75
Polymer brushes
23.87
29.37
31.08
a
Re=100
b
Re=3000
If several quantities that have the same units are repeated in rows or columns, it is clearer to list
the units in the label for that column or row. The alignment tools and table format tools in
Microsoft Word can also be used to make the table clear.
Note that a table is for clearly organizing data. Hence, it rarely contains all of the details related
to the data. For example, Table I above does not describe any of the details of the experimental
measurement such as the temperature and geometry under which these measurements were
made. If they were all measured at the same conditions, this note can be included in the text of
the report or as a footnote to the table, as shown above. If all the conditions are different, these
might be described in another column or in a completely separate table.
Figures
The following are some formatting requirements for figures:
• They should be centered on the page.
• They should be numbered using Arabic numbers (1, 2, 3, etc.)
• They must be called out (introduced) in the text before they appear.
• Do not bold the entire caption. It is acceptable to bold the figure number (e.g.,
Figure 1.) at the beginning of the caption, but bolding the entire caption is not
necessary and can be distracting. See the example on the next page.
• Captions:
o
o
o
o
go beneath the figure
can be detailed if necessary and include more than one sentence.
should be single spaced.
should be in 10-point font.
71
o should use sentence case (i.e., capitalize the first letter of the first word and
then treat the rest of the caption as a regular sentence)
o should always end in a period (even if not a complete sentence)
o should be left-aligned underneath the left-hand edge of the figure and should
not extend past the right-hand edge of the figure.
• No figure labels or title should appear above the figure.
• The figure should NOT be surrounded by an outer border or frame.
• Symbols and lines in a graph should be used appropriately.
o Discrete data points should use symbols(markers)
o Continuous functions that describe theories or models should use lines.
o The only time it is permissible to use a line for data is if the sampling rate of
the data (usually this occurs with computer data acquisition) is very rapid
relative to the graph scale and the data points would blur together, as is often
the case with spectroscopy data.
• Whenever possible, the legend for the figure should be placed inside the figure, as
seen in Figure 1.
o If the legend is simple enough to include in the figure, it should be placed in
the figure. It should never be placed to the left or right of the figure as is the
default for Microsoft Excel.
o If the figure legend is too complicated to fit inside the figure, then you may
define the figure symbols in the caption below the figure, as seen in Figure 2
below. However, it is always better to put the legend inside the figure if at all
possible.
• If the legend is in the figure, put a box around the legend (to differentiate the legend
symbols from the actual data), as shown in Figure 1.
•
Label the x-axis and y-axis with units, etc.
• KaleidaGraph, Excel, or MATLAB (all on the ChBE computer cluster) may be used
to prepare graphs. Figures may not be hand-drawn. Note that Microsoft Word has
easy-to-use drawing tools for apparatus diagrams.
An example figure prepared using Kaleidagraph appears on the next pages.
72
5
4.5
4
3.5
3
2.5
Our Study
2
Smith's Study
Model
1.5
1
0
1000
2000
3000
4000
5000
6000
Re
Figure 1. Measured rate constant vs. Reynolds number (Re)
relative to Smith’s study and the proposed kinetic model.
Error bars on the data from our study are the 90% confidence
limits for the three trials at each value of Re.
73
5
4.5
4
3.5
3
2.5
2
1.5
1
0
1000
2000
3000
4000
5000
6000
Re
Figure 2. Measured rate constant vs. Reynolds number (Re) relative to
Smith’s earlier study and the proposed kinetic model (circles are our
data, open squares are Smith’s data points, and dotted line is the kinetic
model). Error bars on the data from the current study are the 90%
confidence limits for the three data points taken at each value of Re.
** Please note that figure captions should provide sufficient description of the data points,
curves, and error bars. These descriptions may use more than one sentence.
Three graphing packages are supported by Georgia Tech and the School of Chemical and
Biomolecular Engineering Computer Lab: Excel by Microsoft, KaleidaGraph by Synergy
Software, and MATLAB by Mathworks. Of these, the one that produces true publication-quality
graphics is KaleidaGraph. The graphs appearing in Figures 1 and 2 were made with
KaleidaGraph. However, MATLAB and Excel can produce reasonable graphs for most of the
lab report requirements. Adding new sets of data and error bars is not quite as simple in Excel as
these activities are in MATLAB or KaleidaGraph. Once the graph is formatted correctly, it can
be saved or exported in various graphics formats (GIF, TIF, PICT or JPG) to be placed in a word
processor.
Additional annotations to the figures can be made in Microsoft Word once the graph is added to
the report document. Such annotations are particularly helpful in oral presentations.
NOTE: The same detailed captions should not be included on figures and tables for oral
presentation slides, as much of this information will be communicated in the slide title, or
orally.
74
Appendix F: Transitional Words and Phrases
Cues that lead readers forward from information they've already read to new
information.
•
To move readers into additional information or further development of your ideas.
Old
Information
New
Information
Transition
ADDITION
Actually,
Further,
Additionally,
Furthermore,
Again,
Incidentally,
Indeed,
•
And
In fact,
Besides
Lastly,
Equally important,
Moreover,
Finally,
Not only this, but this as well
First, Second, Third, etc.
What's more,
To move readers into specific examples
Generalization
Transition
Examples
EXAMPLES
As an illustration,
Namely,
Especially,
Notably,
For example,
Particularly,
For instance,
Specifically,
Including
To demonstrate,
In particular,
To illustrate,
75
Cues that lead readers through a sequence
•
To move readers from one time-frame to another
One
time
Another
time
Transition
TIME
After a few hours,
Immediately following,
Afterwards,
Initially,
At the same time,
In the end,
Before
In the future,
In the meantime,
Currently,
Last, Lastly,
During
Later,
Eventually,
Meanwhile,
Finally,
Next, Soon after,
First, Second, Third, etc.
Previously,
Simultaneously,
•
Formerly,
Subsequently,
Immediately before,
Then,
To draw readers' attention to a particular location or place
One place
Transition
Another place
PLACE
Adjacent,
In the background,
Alongside,
In the distance,
At the side,
In the front,
Here/There
In the foreground
In the back,
Nearby,
76
Cues that draw readers' attention to cause-and-effect relationships
•
To emphasize a cause or reason
Transition
An effect
move in to
Cause/Reason
CAUSE/REASON
As
Because
Because of
For
Since
•
To stress a result or an effect
Transition
Cause/Reason
An effect
move in to
EFFECT/RESULT
•
As a result,
So that
Consequently,
Therefore
For this reason,
Thus,
To clarify the purpose of something
Transition
Something
move in to
Its purpose
PURPOSE
To
With xyz in mind
So that
To that end
77
Cues that make readers stop and compare what they've just read to what they're
about to read
Just read
Transition
About to read
equal or not equal
COMPARISON/CONTRAST
Although/Although xyz is true
Meanwhile,
And yet
Nevertheless,
At the same time,
Nonetheless,
But
Notwithstanding,
Conversely,
On the contrary,
For all that,
On the other hand,
In comparison,
Similarly,
In contrast,
Still,
In the same manner/way,
While xyz is true
However,
When in fact
Likewise,
Whereas
78
Cues that lead readers into statements that clarify or emphasize
•
To clarify a point that readers have just read
Transition
Point just read
Clarification
meaning
CLARIFICATION
•
In other words,
That is to say,
In this case,
Under certain circumstances,
Put another way
Up to a point
To emphasize a point that readers are about to read
Point just read
Transition
Emphatic point
!!!!
EMPHASIS
As a matter of fact,
In fact,
In any case,
In any event,
That is
Indeed,
Certainly,
79
Cues that lead readers into concessions, reservations, dismissals, or conditions
•
To concede a point that readers are likely to think of
Transition
Point just read
Concession
but maybe
CONCESSION
Admittedly,
While it is true that…
Despite xxx,
In spite of xxx,
•
It may seem that…
To clarify for readers the writer's reservations
Transition
Point just read
Reservation
even so
RESERVATION
•
Admittedly,
Indeed,
As a matter of fact,
Nevertheless,
Even so,
Notwithstanding,
Even though
Regardless
Despite this…
Still
To dismiss a point that readers are likely to think of
Point may be true
Transition
Dismissal
BUT
DISMISSAL
Regardless, In any case/event,
At any rate,
In either case,
Either way,
Nevertheless,
80
To establish a condition or conditions affecting the subject
Transition
The subject is true
This condition is met
IF
CONDITION
Although
Although this is true,
but
Even though,
However,
In spite of
Nevertheless,
Since
Cues that lead readers into an abstract or conclusion
•
To repeat a point you've already made
Transition
A point
Point stated
differently
=
REPETITION
Again,
In brief,
As indicated above/earlier,
In short,
As we stated,
As noted earlier,
As mentioned,
On the whole,
81
•
To summarize what you've already said
Transition
Points made
Abstract
nutshell
ABSTRACT
•
All together,
On the whole,
As mentioned,
Overall,
As stated,
Since
Briefly,
So
By and large,
In short,
Finally,
Then,
Given these facts,
Therefore,
In brief,
To conclude,
In conclusion,
To summarize
To introduce readers to a conclusion or conclusions
Points made
Transition
the end is coming
Conclusion
CONCLUSION
Accordingly,
In short,
As a result,
Consequently, In conclusion,
Finally,
To conclude,
Hence,
Therefore,
In brief,
Thus,
82