_____University of Puget Sound
Department of Chemistry
I. GENERAL LABORATORY AND SAFETY RULES
Your laboratory work is the core of your chemistry course. You have a challenging
opportunity to observe many of the facts of chemistry under controlled laboratory
conditions and to deduce from these observations the basic principles which
constitute the foundation of the science of chemistry. This is putting into use the ideas
of the scientific method.
SOME GENERAL RULES
1. Gain self–reliance by working individually, unless the experiment demands
teamwork.
2. Use your ingenuity and common sense. Laboratory directions, while quite specific,
leave ample opportunity for clean–cut, logical, original, and imaginative thinking. This
attitude is a prerequisite in any scientific endeavor.
3. Don't waste time. Prepare for each experiment by studying it before you come to lab.
4. Prepare the lab report on the current experiment with care. You will use a laboratory
notebook. Use a permanent bound notebook—make data entry tables in advance and
record directly, in ink, into the lab notebook as you obtain it. When calculations are
involved—show an orderly calculation for the first set of data, but do not clutter the
calculation section with arithmetic details. Likewise, think and answer important
questions which have been intended to guide you to an understanding of principles
on which the experimental procedure is based as you perform the experiment. Your
laboratory instructor will give more specific directions for the notebook and lab
reports.
5. Scientists learn by discussing with one another. You may likewise profit from
discussion with your classmates—but not copy from them. The best of all science rests
first in integrity. You can also get help by frequent reference to your text while in the
laboratory.
LABORATORY RULES
1. Maintain an orderly, clean laboratory desk. Invert glassware over a paper towel to
dry. Clean your area with a thorough wash and wipe of the desk top at the close of the
period.
2. Discard solids into the appropriate waste containers. Never throw matches, litmus
paper, or any insoluble solids into the sink. Wash down appropriate liquids into the
sink with water; acids and salts of copper, silver, and mercury are corrosive to lead
plumbing. If you have a question as to the disposal method of any material in the lab,
be sure to ask the instructors, TAs, or the storeroom manager for directions.
3. Leave reagent bottles in the designated area. Bring test tubes or beakers to the area for
transferring chemicals and carrying them to your desk.
4. Read the label twice before taking an anything from a bottle.
5. Avoid using excessive amount of reagent.
6. Never return unused chemicals to the reagent (stock) bottle. You may make a mistake
from which other students’ experiments will suffer.
General Laboratory and Safety Rules
7. Do not insert your own pipets or medicine droppers into the reagent (stock) bottles.
Avoid contamination of the stock solution by pouring the solution from the bottle into
a clean, dry beaker and pipet from the beaker.
8. Do not lay the stopper of a bottle down. Impurities may be picked up and thus
contaminate the solution when the stopper is returned.
9. Do not heat heavy glassware such as volumetric flasks, graduated cylinders, or bottles;
they break easily. Test tubes may break if they are heated above the liquid level and
liquid is splashed over the hot glass. Evaporating dishes and crucibles may be heated
red hot. Avoid heating any apparatus too suddenly; apply the flame intermittently at
first.
SAFETY PRECAUTIONS
1. Maintain a wholesome, businesslike attitude at all times. For the safety of the whole
class, unauthorized experiments are prohibited.
2. KNOW THE LOCATION AND OPERATION OF THE EYE WASH, FIRE
EXTINGUISHER, FIRE BLANKET, AND SAFETY SHOWER.
3. ALWAYS WEAR SAFETY GOGGLES! Wear protective goggles at all times in the
laboratory, as directed by your instructor. Flush corrosive liquid from the eye with
plenty of water using the eye wash fountain for a full 15 minutes.
It is recommended that contacts not be worn in the chemistry laboratory.
4. AVOID DIRECT CONTACT WITH CHEMICALS! If corrosive liquids touch the
skin, flood with water. Consult your instructor immediately.
5. Do not point your test tube at your neighbor or yourself when heating substances. A
suddenly formed bubble of vapor may eject the contents violently.
6. Do not hold your face directly over an container when noting the odor. Instead, fan a
little of the vapor toward your nostrils by sweeping your hand over the top of the
container.
7. NO FOOD OR DRINK ALLOWED in the laboratory. Do not put anything in your
mouth until you have washed your hands and left the room. Never taste a chemical or
solution in the chemistry lab. (Poisonous substances are not always so labeled in the
laboratory.)
8. Beware of hot glass and glass tubing - it looks cool long before it may be handled
safely.
9. Use the fume hood for reactions involving poisonous or noxious gases. It is a device
that provides suction to remove such gases or vapors.
10. To insert glass tubing (including thermometers, thistle tubes, etc.) through a rubber
stopper, first lubricate the tube and stopper with water (unless moisture must be
avoided) or glycerin. Hold the tubing with a cloth near the end to be inserted, and
insert with a twisting motion. (If you twist a thistle tube by the "thistle" end, it is easily
broken.)
11. ACID SHOULD ALWAYS BE POURED INTO THE WATER, not the other way
(water into the acid). When diluting sulfuric acid, pour the acid slowly into the water,
never the reverse order. So much heat is liberated in forming the solution that steam
may form with explosive violence.
12. Protective clothing must be worn when working in the laboratory. If clothing that
exposes bare skin is worn, then a laboratory apron or laboratory coat is required.
SANDALS AND/OR OPEN–TOED/OPEN-HEELED SHOES are NOT allowed in the
laboratory.
13. Report even minor injuries to your instructor at once.
General Laboratory and Safety Rules
_____University of Puget Sound
Department of Chemistry
II. LABORATORY NOTEBOOKS
In Chemistry 110/111 and in Chemistry 230, your laboratory work will be
evaluated from various documents. Each experiment will require you to hand in
copies of the appropriate pages from your notebook. Some later experiments will
require more formal laboratory reports, separate from your notebook. In each case, a
good laboratory notebook is the foundation to being able to communicate your results
effectively and accurately.
Depending on the situation in which a laboratory notebook is used (e.g. CHEM
110 lab, undergraduate or graduate research, industry, etc.) it can serve many
different functions.
1.
It serves as a reminder of the experimental procedure.
2.
It is a record of all your data: measurements, calculations and observations.
3.
It can be a legal document. If you are involved in research, it can help establish
that you were the first to make a certain discovery, which is important when
patent and publication rights are involved.
4.
It is a scratch pad for your calculations.
5.
It is your personal record. Feel free to jot down notes relating to classroom
discussion, personal comments, queries, book references, your partner's phone
number, etc. This is a working document, not a final, perfect, ready-forpublication one! On the other hand, you should be able to make sense of all
your entries even six months later.
6.
It may be the document on which your lab performance is graded. Therefore it
should be easy for your TA or instructor to find what they are looking for in
your notebook, and to follow what you are doing. In making notebook entries,
you should always keep these readers in mind – they know some chemistry but
are not mind-readers!
GUIDELINES FOR USING YOUR LABORATORY NOTEBOOK
These guidelines apply to all entries, whether made before, during or after the lab
session.
***WRITE YOUR NAME AND SECTION CLEARLY ON THE OUTSIDE OF YOUR NOTEBOOK.***
1.
All data should be entered directly into the notebook, in permanent ink. Take your
notebook to the balances with you; don't try to remember a weight until you get
back to your bench, and don't write it down on a scrap of paper as an interim
device. Every time you transcribe something there is a chance of making an error,
Chemistry Laboratory Guidelines-Laboratory Notebooks
1
and in any case you might just lose the piece of paper! Do not rely on your lab
partner to record the data. Write it in your own notebook!
2.
All pages must be numbered.
3.
Entries should be provided with units and appropriate labels. A weight on its
own (e.g. 3.16 g) is totally inadequate. Is it a flask or a weighing bottle, and
what are its contents, if any? Entries like 3.16 g Fe and empty vial and cap =
13.7670 g are more meaningful.
4.
An erroneous entry or other mistake should never be erased or obliterated. Just
draw a neat line through it. Don't overwrite a number - write the correct
number next to the deleted one. Don't destroy or tear out the white original
pages - if necessary, neatly cross out the entire page. A brief annotation of the
reason for striking out the page may be helpful to the reader.
5.
For a series of calculations of the same sort, always show one sample
calculation. This will remind you how it was done, and will enable your TA or
instructor to pinpoint errors and alert you to them.
ORGANIZATION
Table of Contents
Reserve the first four pages of your notebook for a Table of Contents. Leave plenty
of room throughout the notebook, including the Contents section. Remember to
update this section as new labs appear in the book.
General
Each experiment should begin on a new page and be headed by its title, date(s),
lab section, your name, TA's name and the name of your lab partner, if any. Keep
different experiments well separated from one another. In CHEM 110 labs you will
usually be given fairly detailed instructions as to what should be entered in your
notebook before the lab, during the lab, and after the lab. In later courses, you will
have to decide on these things yourself.
Try to keep your notebook reasonably neat, but this should not be the overriding
objective. Good organization is far more important – keep various sections separate
and identifiable, such as: procedures; raw data and observations; calculations;
answers to questions, etc. To facilitate grading of your lab notebook, it will often be
useful to reserve a page or two at the end of the experiment for collecting all
important "final" results and answers to any questions posed in the laboratory
experiment.
Figures, including rough graphs, may be drawn directly in the book; loose-leaf
material such as computer printouts and accurate graphs on graph paper, provided
that there are not too many of them, should be neatly taped into the notebook.
Before Lab
Each lab will provide a list of what you need to do in your notebook before coming
to lab. If you have not completed this part of the notebook before lab time, you must
do so before we will allow you to start the experiment. Coming unprepared and/or
starting the experiment late is unlikely to endear you to your TA, your instructor or
your lab partner.
Chemistry Laboratory Guidelines-Laboratory Notebooks
2
In the Lab
Again, you will get instructions with each experiment as to what entries to make
in the notebook. Note any changes to the actual procedure as compared to what is
written in the procedure from the manual. Record all data obtained during the lab
session, make appropriate notes and calculations.
After the Lab
The report will generally need to be completed after the lab. This may involve
calculations, comparison of your results with published data, drawing neat graphs
and answering specific questions. You will get appropriate instructions, but you will
also get credit for showing initiative in going beyond the minimum requirements.
While you may work with a partner, each of you is responsible for turning in separate/original
work on all written material.
Chemistry Laboratory Guidelines-Laboratory Notebooks
3
_____University of Puget Sound
Department of Chemistry
III. INTRODUCTION TO WRITING IN THE CHEMISTRY
LABORATORY
In addition to fostering a sense of scientific inquisitiveness and supporting the
learning experience in the lecture portion of the course, the laboratory experience in
this and many other chemistry courses is used to teach effective written
communication. Skills required for scientific communication include such things as
the ability to record data properly and prepare tables and graphs in addition to
developing the ability to write clearly and concisely. In CHEM 110 lab we will focus
on the basic “pieces” as well as the overall structure of a lab report. Each week, the lab
will emphasize a particular aspect of notebook keeping and/or report writing. For
example, during one week we will learn proper graphing and figure format and in the
next week we will learn to organize data in a table using a computer spreadsheet.
Toward the end of the semester we will put all the pieces together and write a lab
report modeled on the format that chemists use to publish reports of laboratory
experimentation and research in professional journals.
Along with pre-lab lectures given by your instructor and teaching assistant (TA),
each of the laboratory experiments in this manual will address the specific writing
aspect of the lab being emphasized that week. Pay particular attention in your pre-lab
preparation to the “What to Do” sections in the handout. “Writing” assignments may
be found as lab preparation (Before the Lab), while doing the experiment (In Lab), at
completion of the experimental work (Before Leaving the Lab), and before turning in
the weekly report (After Lab).
The guidelines and techniques that are to be used and developed during the
semester are presented here in the beginning of the laboratory manual so they will be
easy to find. They will constitute a comprehensive set of guidelines for writing
chemistry lab reports.
Writing in Chem 110 Laboratory–Introduction
_____University of Puget Sound
Department of Chemistry
IV. GUIDELINES FOR MAKING TABLES
INCLUDING A TABLE OF REAGENTS
Tables are a very useful way to present large amounts of data (information) in a
compact, organized format. The data may be of various types, including such things
as names and formulas of chemical compounds, qualitative (non-numerical)
information, such as the color and physical form of a substance, and quantitative data
which could include both direct experimental measurements (e.g., mass, length, time,
temperature, etc.) and the results of calculations based on these measurements (e.g.,
length
speed = time ).
For many of the experiments in this course the results need to be summarized in a
table in your notebook on the final page of the experiment. This serves to assist you in
organizing and displaying the relevant results, as well as giving the person evaluating
your work a consistent place to look for the results.
TABLES IN LABORATORY NOTEBOOKS
When preparing a data table in your notebook, think ahead about what column
headings are needed and how much space will be required both horizontally and
vertically. Always leave enough room to make corrections, do additional trials, etc.
Tables in Lab Notebook ≠ Tables in Formal Reports
Keep in mind that a logical table for the collection of data may not be the most
suitable way to present data in a formal report. Column headings in a table in the
PreLab are for data collection and may need modification for a table in a formal report
Example of an incomplete Data Table
Table 1. Calculated Spectral Wavelengths
ni = 6
ni = 5
|∆E| (J), (nm) |∆E| (J), (nm)
nf = 1
ni = 4
|∆E| (J), (nm)
ni = 3
ni = 2
|∆E|(J), (nm) |∆E| (J), (nm)
2.229 x 10 - 18
2.119 x 10 -18
93.98
nf = 2
nf = 3
nf = 4
nf = 5
nf = 6
Guidelines for Tables
Table of Reagents
In the chemistry lab, safety and chemical disposal are extremely important. You
will be working with various reagents, some of which are potentially hazardous. It is
a good practice to know something about the properties of these substances before
you are in contact with them. Organizing a Table of Reagents in your notebook
allows you to have information about the chemicals that you are working with.
Please note that the Table of Reagents generally follows the table guidelines
(numbered, title, etc.) but can have vertical lines inappropriate for a formal report
table.
Example of an incomplete Table of Reagents
Table 2. Table of Reagents
Formula
Name
Mol. Wt.
(g/mol)
Physical form
and color
Solubility
in water
Disposal
Safety,
hazards, etc.
Cu
copper
63.55
reddish solid
insoluble
In labeled
waste
NON-TOXIC
Zn
Zinc
HNO 3
Nitric acid
NaOH
Sodium hydroxide
H 2 SO 4
Sulfuric acid
98.08
colorless solution
soluble
H 2*
Hydrogen
NO 2 *
Nitrogen dioxide
CuO*
Copper (II)oxide
* Compounds
formed but not isolated
In sink w/ Corrosive, Reactive
water
This is a basic reagent table. This table may be expanded to include additional
columns for the amount of reagent required, the amount of reagent used, and the
number of moles of reagent used.
Most of the required information can be found in references available in the
chemistry library, the main library, and some approved chemical websites. Some of
the resources are:
Wikipedia
Handbook of Chemistry and Physics
The Aldrich Catalog
The Merck Index
Guidelines for Tables
TABLES FOR FORMAL REPORTS
As an example of a table formatted for a formal report, consider the following
table adapted from one in your text.
Table 3.
Fundamental Subatomic Particles
Particle
electron
proton
neutron
Symbol
ep+
n0
Chargea
-1
+1
0
Mass (amu)
0.0005486
1.007276
1.008665
a Charges are in multiples of the proton charge, 1.6022 x 10-19 C.
Note the following important points, which are inherent in all good tables.
1.
2.
3.
4.
5.
6.
7.
The table is numbered. There should be reference (or references) to the table, by
number, in the text of an article or report.
The table has a title which gives a good indication (though not necessarily a
complete description) of what it deals with. When you devise a table, avoid
redundant words (such as “Table showing the results of…”) but be informative
and unambiguous (titles such as “Results obtained in Part 2” are not very
helpful or clear).
Each row generally deals with a single item (in this case a particle, but it could
also be a single experiment, a single measurement made on a particular object,
etc.)
Each column has an appropriate heading which describes what data the
column contains.
Where the data in a column is a physical quantity (such as mass, in column 4) it
is essential to report both the numerical part (e.g., 1.007276) and the unit part
(amu, or atomic mass units). It is good practice to show the units just once, in
brackets, in the column heading. Otherwise the units must be written after
every entry in that column, which wastes time and clutters up the table.
If any part of the table needs additional explanation, this is conveniently done
using a footnote, as with the heading of column 3.
Include lines between the table’s title and the entry headings, between the
entry headings and the data, and at the bottom of the table. Tables in formal
reports have only 3 horizontal lines, never any vertical lines (however in your
notebook more lines may help keep data together.)
The general style of this example should be followed when you construct tables in
formal laboratory reports. This format is used in the Journal of the American Chemical
Society, JACS, and many other scientific journals and is the standard way tables of
data are presented in scientific literature.
Guidelines for Tables
_____University of Puget Sound
Department of Chemistry
V. GUIDELINES FOR FIGURES
GENERAL
A “figure” in a scientific article or book may be any one of several different types
of illustrations. A glance at your chemistry textbook will reveal that a figure may be a
photograph, a drawing of an apparatus, a representation of atoms or molecules, or a
graph showing the relationship between different variables. Despite this variety of
flavors, all figures share certain common features, listed below. Make sure that all
figures in your lab reports meet these requirements!
1.
Like a table, a figure should be numbered and have a caption which is a short
sentence or phrase outlining its contents. Avoid starting with redundant words
such as “A figure showing ….” Please note that the table number and title are
above the table while the figure number and caption are below the figure.
2.
The figure and its caption should be capable of standing alone; the reader
should not have to read the accompanying text in order to understand the
figure.
3.
The caption text should direct the reader’s attention to important features.
GRAPHS AND PLOTS
In your lab reports, the most common type of figure is likely to be a graph. For this
reason, we will deal with graphs in more detail. Most often, a graph shows a
relationship between two physical quantities; in Figure 1, these quantities are pH and
volume of NaOH solution.
15
10
pH
5
0
0
10
20
30
40
Vol. NaOH (mL)
Figure 1. Titration curve for an unknown weak acid with 0.0100 M NaOH. The
equivalence volume is at 25.24 mL.
Notice that the best smooth curve is drawn through the data points. This is not the
same as connecting the dots; if any points are clearly away from the trend line, the line
Guidelines for Figures
should not be forced to go through them. When a plot is drawn or sketched in your
notebook or drawn by hand the rules are not as rigid. The line drawn is sometimes
visually estimated (“eyeballed”) and sometimes calculated from an appropriate
mathematical expression. Here are a few of many essential features of a good graph.
1.
2.
3.
4.
5.
Each axis must be labeled with the quantity being plotted and its units,
and must have a regular scale. In the sample graph, above, the ordinate
is labeled pH. Note that pH has no units. The scale is in equal
increments from 0 to 15. The ordinate is the vertical axis or the y–axis.
The abscissa is labeled Vol. NaOH (mL) and the scale runs from 0 to 40
mL. The abscissa is the horizontal axis or the x-axis. By convention, we
say that y is plotted versus x (i.e., pH versus volume of NaOH in this
case); not x versus y.
The data points are never plotted only as little dots. One may use small
circles, squares or triangles (open or filled), crosses or a variety of other
symbols. Dots alone are too easily lost on the graph or “created” by stray
blobs of ink.
In a formal report the plot should be displayed without a legend, no
gridlines and no fill in the background.
For hand drawn graphs all lines and data points must be drawn in ink.
NEATNESS COUNTS!
The scales of the axes should be adjusted so that the graph fills the page
as much as reasonably possible.
When doing hand drawn plots using graph paper, do not write in the
margins – inset the axes from the edge of the grid area The axes need not
start at zero; the paper should be used as efficiently as possible. Use a
logical scale to make it easy to plot points or to read them off (one
square = 1 or 2 or 5 units, or some 10x multiple, rather than 1 square = 3
units, etc.)
One should be able to interpolate accurately between the graph paper’s
ruled lines when plotting points or when reading values off the graph.
Thus, for the best hand drawn plots you should use graph paper with
lines ≤1 mm apart rather than some coarser spacing.
LINEAR PLOTS
Where possible, we attempt to plot data so that the points lie on a straight line. It is
then very easy to check, by visual inspection, whether the data do indeed lie on a
straight line or not. Also, it is very easy to interpolate between data points if they lie
on a straight line.
If you recall, the formula for a straight line is
y = mx + b
In this equation the b represents the y-axis intercept, which is the value of y where
the line crosses the y–axis (x = 0). The slope, m, is positive when the line slopes up
from the left to the right (/) while a negative value of m is associated with a line that
slopes up from the right to the left (\). The slope can be calculated by choosing two
points, (x1, y1) and (x2, y2), and applying the formula shown in Figure 2. To achieve an
accurate result in such calculations, the chosen pair of points should not be actual data
Guidelines for Figures
points as well as being separated as much as possible. When calculating the slope of a
graph for a report, be sure to show your work, not just the end result.
(x 2, y 2)
y
!y
(x 1, y 1)
b
m = slope =
!x
!y
!x
y2
= x
2
-
y1
x1
x
Figure 2. Example of a linear plot of the form: y = mx + b and the calculation of the
slope, m. Note the values selected for x1, x2, y1 and y2 are not actual data
points but values from the line.
Another, more important, reason for seeking a straight line relationship in one’s
data is that the slope and intercept often have important theoretical meanings. For
example, plotting the mass against the volume, for water samples, gives a straight
line with a slope equal to the density. In the following example, a Beer’s Law plot, the
slope can be used to calculate the concentration of solutions with an unknown
concentration.
Figure 3. Plot of Concentration vs. Absorbance for a sample of food dye, Red#40 from
LoggerPro. A linear regression is shown with a slope of 1.17 ± 0.01.
Guidelines for Figures
_____University of Puget Sound
Department of Chemistry
VI. GUIDELINES FOR WRITING THE EXPERIMENTAL SECTION
OF A REPORT
GENERAL
The most important thing about the Experimental section is that it sets out what
actually happened in the lab, which might be different from what was in the lab write
up in the manual. For this reason, it is always written in the past tense and the passive
voice. Here is a good example,
The aluminum wire was dissolved in 2 M hydrochloric acid.
and here are two poor examples,
Dissolve the aluminum wire in 2 M hydrochloric acid.
We dissolved the aluminum wire in 2 M hydrochloric acid.
The layout of the Experimental section depends on the type of chemistry being
reported, but some general guidelines usually apply. It is often appropriate to divide
the section into a General section and a Procedures section. The General section
describes methods and materials common to several experiments, and includes
information on special instruments used, but doesn’t include common laboratory
equipment like balances. If the instrument is a spectrophotometer, for example, you
would include the make, model number, settings (like wavelength), and conditions
(temperature and pressure). The Procedures section describes the experiments
performed, with a separate paragraph for each step or reaction.
On the next page is a “sample” Experimental section for a Copper to Copper lab
similar to the experiment you did earlier this year. You can see from reading it that
the writing style is so concise it is almost simplistic. Don't worry about beautiful
English, just try to get the essential information across as clearly and briefly as
possible. In trying to decide on the level of detail, think about a student with your
chemistry skills who hasn't done this particular lab. There should be just enough
detail for someone like you to repeat the work.
AGAIN PLEASE NOTE: While you may work with a partner, each of you is responsible for
turning in separate/original work on all written material.
Guidelines for Writing the Experimental Section
Revised10/07
EXPERIMENTAL
General
All chemicals were purchased from Aldrich Chemical Company and used without
further purification. Unless noted, all reactions were performed at room temperature
and at atmospheric pressure. The ultraviolet-visible spectra were measured using a
XYZ spectrophotometer (Model 123) with deionized water as the blank.
Procedure
Reactions of copper
Nitric acid (6 M, 5 mL) was added to copper wire (0.173g, 2.73 mmol), in a 50 mL
Erlenmeyer flask. The flask was placed on a hot plate in a fume hood until dissolution
of the copper was complete. The blue solution was then cooled under running water
before it was diluted with 5 mL of distilled water.
Sodium hydroxide (6 M) was added dropwise to the above solution, with stirring,
until the mixture was basic to red litmus paper. A pale blue precipitate of copper (II)
hydroxide resulted.
The Erlenmeyer flask was placed in a 150 mL beaker, half-filled with boiling
water, on a hot plate. The contents of the flask were stirred intermittently for 10
minutes, converting the hydroxide to black, solid, copper (II) oxide. Excess liquid was
removed by decantation, and the precipitate was then washed by decantation with
successive portions of distilled water (3 x 25 mL).
Sulfuric acid (3 M, 15 mL) was added to the solid copper oxide, and the mixture
was stirred to dissolve all the solid. The blue solution of copper sulfate was
transferred to a 100 mL beaker.
Magnesium metal turnings (2.1 g, 86.4 mmol) were added in portion to the copper
sulfate solution, in the hood, with occasional stirring. When the blue color of the
solution had entirely disappeared, sulfuric acid (3 M, 15 mL) was added to dissolve
excess magnesium. The supernatant liquid was decanted from the solid copper
powder which was washed, by decantation, with distilled water (3 x 5 mL). A final
wash and decantation was done with 5 mL of ethanol. The copper was transferred to a
watch glass, and dried overnight before weighing (copper recovery: 0.159 g; yield
91.9%).
Ultraviolet-visible spectra of the aqueous solutions of copper(II) nitrate and
copper(II) sulfate were collected. Each sample was transferred to a cuvet, placed into
the spectrophotometer, and the wavelength of maximum absorbance (λmax) was
recorded.
Some important points about this example
1.
Details of technique are not given. For example, it is presumed that the reader
knows how to do a decantation, or at least is able to find out for him/herself.
2.
Although results belong in the Results section, it's OK to make a few brief
observations in the Experimental Section such as % yield, if they seem useful
and do not interrupt the flow. For example, in the second step above the author
mentions a "pale blue precipitate" because it would be useful for someone trying
to repeat the work.
Guidelines for Writing the Experimental Section
Revised10/07
_____University of Puget Sound
Department of Chemistry
VII. GUIDELINES FOR WRITING THE RESULTS AND
DISCUSSION SECTIONS OF A REPORT
GENERAL
Depending upon the author of a report, or to some extent the nature of the subject
matter, there may be a section that combines Results and Discussion into one section,
or there may be a separate sections for Results and Discussion. Inspection of scientific
journals reveals that both formats are commonplace, and still other journals have a
combined "Results and Discussion" section followed by a section entitled "Summary."
There are good arguments for adopting each of the formats mentioned above,
however, in the interest of helping you to understand the components of each you
will be initially asked to write separate Results and Discussion sections.
RESULTS
As a guide to keeping Results distinct from Discussion, you may want to
remember that Results are Results. No involved interpretation of results should be
contained in this section. Normally, the Results section summarizes the data you have
collected and consists chiefly of elaborations of the information in Tables, Figures, and
Schemes. If the results are stated objectively, then readers (not necessarily experts in
the field) are allowed to draw their own conclusions. Results that are clearly
presented make it possible for the author to be persuasive or convincing when the
Discussion (and conclusions) are finally stated. It may be a good idea to present
Results in a way that guides the reader to a reasonable interpretation, without leading
them directly and forcefully to agree with your conclusions. In this sense, information
presented in Results are not arguable, or speculative, and the reader is allowed to
have some measure of discovery, something to which they may feel entitled.
The Results section comes immediately before the tables and figures that are being
introduced. The Results section is predominantly written in the past tense (e.g., "the
samples were clear and brightly colored"), but references to data Tables, Figures, or
Schemes are generally in the present tense (the wavelength of the absorption
maximum for each sample is apparent from Figure 3, and the values are summarized
in Table 2). It is important, however, to use text to introduce each Table, Figure, or
Scheme, explicitly, such as in the following examples:
EXAMPLE 1.
The results of the experiment to measure the mass and charge of three
fundamental particles are summarized in Table 3. (please refer to Guidelines for
Making Tables).
EXAMPLE 2.
The titration of a weak acid with a strong base is shown in Figure 1. (please refer to
Guidelines for Making Figures).
Guidelines For Writing the Results and Discussion Sections
DISCUSSION
Discussion of results is just that – you discuss the hard facts presented in the
Results section in a way that allows the reader to make sense of them. If you have
measured the wavelengths of light emitted by an atom, for example, you might
compare your values with the literature (Always reference any literature values
used!). Theoretical analysis is appropriate here. For example, if you have measured
the volume of a gas at different pressures, you may wish to discuss whether your
results are consistent with the ideal gas law. If you have been attempting to identify
an unknown substance, this is where you make your case about what you think it is,
referring of course to data presented in the Results section. It is your responsibility to
convince other interested chemists that the conclusions you draw are valid and make
sense based on the data presented in the paper. The Discussion is usually in the
present tense.
The final paragraph of the Discussion Section may contain a brief summary of the
major results along with their significance. The object is not to merely restate the
results, but to give the reader a feeling for the broader significance of the results. In
this sense, whereas the Introduction to your report provided the context for the
results and discussion, the last paragraph states the relevance, importance, and
significance of the results.
Guidelines For Writing the Results and Discussion Sections
_____University of Puget Sound
Department of Chemistry
VIII. GUIDELINES FOR WRITING THE INTRODUCTION TO A
FORMAL LAB REPORT
The introduction explains why the experiment described in the paper is interesting
and important. What is the motivation for doing the experiment? The answer to this
question will often require a historical account describing previous research along
with appropriate references. It is the author's responsibility to convince other chemists
of the value of this work.
The introduction provides a clear statement of the problem or project. The author
outlines the strategy and the theoretical background for the experiment and puts it in
a chemical context. Reaction equations or chemical Laws should be properly inset and
numbered. Known chemical properties to be used in the experiment should be
referenced. An explanation of the plan to use these reactions, Laws or properties to
answer the question of the experiment is appropriate material for the introduction
Present and past tenses are correct in the introduction. For example, “Absolute
rate constants for a wide variety of reactions are available. Jones reviewed the
literature and gathered much of this information1”.
For examples of some Introductions see the Introduction sections of the chemistry
labs from this semester. These are somewhat lengthy as compared to what is expected
of your Introduction sections, but they generally do follow these guidelines.
Guidelines For the Introduction of a Formal Report
_____University of Puget Sound
Department of Chemistry
IX. GUIDELINES FOR TITLE FORMAT
The purpose of the title bar is to quickly inform the reader what your work is
about, who performed the research, and when. The title should be descriptive and
concise.
Please use the following title bar for any computer generated work that you will
hand in. To conserve paper, the introduction (or whatever is requested) should
immediately follow the title bar (in other words, the title bar should not be on a
separate page). Full names, not just first names, should be employed.
Title (in bold)
Your name* and partner’s name (if applicable)
CA’s name and Lab Instructor’s name
Course number and section
Date
Example
Investigation of the Alien Landing at Roswell, New Mexico
Ima Scientist* and Maya Partner
Jodie See-ay and Professor Frankenstein
CHEM 110 ZA
October 23, 2020
Guidelines For Title Format
_____University of Puget Sound
Department of Chemistry
X. GUIDELINES FOR REFERENCES
References are used to acknowledge sources of background material (possibly
provided in the introduction) or as supporting material in the discussion section.
Scientific articles generally cite primary literature—books and peer-reviewed articles—
and not websites. Websites are generally not peer reviewed, so they are not used as
viable references. A website may provide references back to primary literature (so
check those primary references and reference them, and not the website). There are
some databases of material that may be reference (such as the Crystallographic
Database).
When providing a reference, please use the Journal of American Chemical Society
(JACS) format.
Books
Authors’ names Book Title; Publisher: City, year; pages.
Example
Silberberg, M. S. Chemistry: The Molecular Nature of Matter and Change, 4th ed.; McGraw-Hill: New
York, 2006; pp 542-551.
Articles
Authors’ names, Journal, year, volume, article pages
Example
Smith, J. R. Science, 2005, 402, 1234-5678.
Referencing web sites
Author (if any). Title of Site. URL (accessed Month Day, Year), other
identifying information (if any).
Example:
U.S. Environmental Protection Agency. http://www.epa.gov (accessed Nov 19,
2010).
The references are numbered in the order presented in the article and are
organized into endnotes.
Guidelines For References
_____University of Puget Sound
Department of Chemistry
XI. GUIDELINES FOR WRITING A
COMPLETE FORMAL LAB REPORT
Chemists often communicate the results of their research by publishing a paper in
a chemical journal. These research papers have a definite style and are divided into
defined sections. The formal lab reports which you will write are modeled on the style
of research papers. Most often you will be asked to write only specific sections, such
as an Experimental section and a Results section, thus your reports will generally be
shorter in length than a complete research paper. (Thank goodness!)
A complete formal lab report for CHEM 110 and CHEM 230 includes the following
sections:
1.
Title
(refer to Guidelines IX)
2.
Introduction
(refer to Guidelines VIII)
3.
Experimental
(refer to Guidelines VI)
4.
Results and Discussion
(refer to Guidelines VII)
5.
References
(refer to Guidelines X)
6.
Appendices
(refer to Guidelines XI)
Before you sit down to write a formal report or a specific assigned section, review
the pertinent set of guidelines related to each section. Then decide, broadly, how you
are going to divide the material you present into the different sections. Before writing
any section, have a plan in mind for the material that will appear in the section, the
sequence you are going to follow, the particular points you want to make. It is often
easiest to write the sections of a complete report in the following order:
•
Write the Experimental section—this section includes what you did in
enough detail for someone else to repeat the experiment.
•
Write the Appendix—this section is a final draft of your calculations
showing one neat sample of each calculation you do to get your results.
Often the calculations can be done in your lab notebook and you can
turn in the copy pages from your notebook as an Appendix. You do not
need to include this appendix in the electronic copy submitted to
turnitin.com.
•
Write the Results and Discussion section—the Results section includes
what you found out. You may need to organize your findings with
Tables (refer to Guidelines VI) or Figures (refer to Guidelines V). When
you present data, consider whether the data is best summarized in a
table or figure. Be sure you are familiar with the Guidelines for tables
and figures before proceeding. Often a good presentation of these data
will be to put measurements in one Table and calculation results in
Guidelines For Writing a Complete Formal Lab Report
another Table. Be sure to refer the reader to any sample calculations in
the Appendix.
The Discussion section explains the meaning of your results and points
out generalizations and relationships regarding your observations. Do
not give a step-by-step description of your calculations. Be sure to justify
your conclusions according to any outside sources (properly referenced)
and to the theoretical basis of the experiment presented in the
introduction. This is also the place to comment about any problems
encountered and their possible effect on your results.
•
Write the Introduction. Describe why the experiment is interesting
and/or important. Explain the background and strategy of the
experiment well enough that the reader has an idea of what the
succeeding Experimental section and the Results section are describing.
•
Finally, write the Reference section and the Title.
One way to evaluate your overall writing is to critique your paper with the
following considerations in mind:
1.
Ideas and content, which judges whether a paper is clearly focused on a central
theme.
2.
Organization, which determines whether the writer presents information in a
logical and compelling order without redundancy.
3.
Voice, using to the correct voice for each section.
4.
Word choice, which urges writers to use words that are precise, interesting and
free of clichés.
5.
Sentence fluency, which reveals an easy flow and rhythm when read aloud.
6.
Conventions, which determines whether the writer has a good grasp of
grammar, punctuation, spelling, paragraphing and other conventions of
writing
Formal lab reports or specific assigned sections should be typed and double
spaced into the template. You can overwrite the template or copy and paste into it,
making sure that the paste uses the destination format. Be sure to delete the original !
Use your favorite word processing software and be sure to run a spell check on the
report. With the help of modern technology, there is no excuse for spelling errors in a
formal report.
AGAIN, PLEASE NOTE: While you may work with a partner, each of you
is responsible for turning in separate/original work on all written material.
Good Luck!
Guidelines For Writing a Complete Formal Lab Report