Your Chem 1B Laboratory Notebook
It takes practice and lots of trial and error to keep a good laboratory notebook. Proper lab notebook
techniques are expected in a professional research laboratory.
On the front cover of the notebook write:
1.
2.
3.
4.
5.
your name
chemistry 1B
instructor’s name
your lab drawer number
section #, semester and year
Record everything in your notebook in permanent blue or black ink. Record data directly into your
notebook. Do not use scratch paper for collecting data.
The Table of Contents should always be kept up to date. Write the experiment title on the line and the
page number corresponding to the first page of an experiment.
Start the first lab report on page number 1. Write only on the numbered (right-hand) pages only and do
not use the backs of pages as scratch paper. Always make sure the carbon copy is readable. Each new
lab report should be started on a fresh page. If a mistake is made, cross out the erroneous entry with a
single line (never use white-out or scribble something out). Nothing should ever be deleted from a lab
notebook.
The headings should be filled on the first page only of an experiment. Write your name and the date in
the appropriate boxes. When you work with a partner, enter your partner’s name in an unused box.
Your signature at the bottom of the page is not required.
Your lab notebook will be inspected by the instructor during the lab. If you have an incomplete
notebook you may be asked to leave the lab. The yellow (tear out) pages will be turned in for grading
for each lab report. These pages must be stapled in numerical order with any other required materials
(graphs, spectra, etc.) thoroughly labeled and placed at the end. Graphs must be printed using a
computer graphing program. Do not draw graphs on the lab notebook pages.
Procedure for Graphs:
Graphs are best when they are to-the-point and easy to read.
The following features should be present on the graph:
 Put the title of the experiment, a colon, and then the title of the graph at the top of the page. For
example: Rate Law Determination of the Crystal Violet Reaction: Concentration of Crystal
Violet vs. Time (Run 1)
 If more than one set of data will be plotted, use a legend in an open space on the graph that
shows which symbol refers to which set of data. Label each data set. You should not use a
legend if there is only one set of data.
 Even if you fit a line or a curve to the data, clearly show all relevant data points.
 Label the x- and y-axes with the appropriate labels, including units in parenthesis. Generally the
x-axis should show the independent variable and the y-axis should show the dependent variable.
For example if you are plotting time and concentration, time is not dependent on concentration,
concentration is dependent on time. Therefore, time is the independent variable (x-axis) and
concentration is the dependent variable (y-axis).
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Make sure that the scale of each axis is appropriate. Be careful not to make the scale too big or
two small.
The size of the graph should be appropriate for the type of data set(s). Sometimes it is necessary
for a single graph to be printed on a letter size paper, but in many cases, four smaller graphs
printed on a page is more appropriate.
When writing in your lab notebook avoid the use of the personal “I” and the future tense. Rather, use
impersonal passive scientific wording. For example, instead of saying “I added 5 g of copper(II)
chloride…” or “I will add 5 g of copper(II) chloride …” say instead “5 g of copper(II) chloride were
added…”
The criterion used in judging what should be in a lab notebook is that what is written should be
sufficiently thorough and well organized so that anyone who reads the experiment can understand it and
figure out exactly what was done and what the results were. It should be possible to repeat the
experiment based on what is in the notebook.
Introduction:
Give a brief introduction of what will be done in the experiment and the goal or objective of the
experiment. This step should take no more than a few sentences of a short paragraph. To write a good
introduction, you must figure out the point of the experiment. Students who write their introductions
without understanding what they’re trying to accomplish end up with unacceptable introductions.
Plagiarism: Don’t copy from your handout or text. It is still copying if you change a few words (be
especially careful not to include jargon that you don't understand). In the introduction, the ideas must be
yours, and in your own words.
Example of an acceptable introduction:
“In this experiment, the percent composition by mass of sulfate in an unknown sample will be
determined. Barium chloride will be used to precipitate the sulfate from the soluble unknown
and the percent composition sulfate in the unknown will be determined using gravimetric
methods."
Procedures and Observations:
Procedures are an abbreviated recipe in your words that you and anyone who reads your notebook can
follow. Write out every step, but you don't have to put in every detail. For example, if the text says:
"Place about 10 mL of the standard 0.1 M NaOH in one of the 100 mL clean, dry beakers from your
locker. Use this NaOH solution to rinse the 25 mL pipets by drawing several small portions of the
solution into the pipet and rolling it around to touch all the surfaces."
The procedure might read:
"Use about 10 mL of the 0.1 M NaOH solution to rinse the 25 mL pipet. Make sure all surfaces of the
pipet have been rinsed with the solution."
Observations are written while you're doing the experiment. It may seem as though you're just rewriting
things from the procedures side of the page, but you'll be adding details, the correct significant figures,
and explanations.
An appropriate observation would read something like, "Added 8.94 g of ethyl acetate to the reaction
flask."
Using the dividing line that runs down the center of the notebook pages divide the procedure and
observations sections as follows:
Procedures:
Under the left-side heading write out the steps of
the procedure in outline form. If any changes are
made to the procedure given in the reference, be
sure the procedure here is the one you actually
followed (don't just write what the lab says to do
if you actually did it a different way or made
changes).
Observations:
Under the right-side heading write out the
corresponding observations as they happen. Be
brief, yet, clear and thorough. Observations
should include aspects of the procedure as it is
carried out and results are obtained. For example,
changes in state, color, texture, odor, rate,
temperature, etc. should be recorded. Be sure any
numerical values are recorded with units.
Leaving too little space between procedures is a common mistake. On the observations side of the
notebook, you'll be putting in a lot of information like numbers, descriptions, tables, etc, so make sure to
leave plenty of space between directions in the procedure. If there is not enough space for these things,
you'll end up trying to squeeze things in or running out of room. It is better to leave more space than
you think you'll need.
PROCEDURE
OBSERVATIONS
Weigh a 10-mL graduated cylinder.
Weighed a 10-mL graduated cylinder.
Tare weight = 8.687 g
Add 5 mL of isopentyl alcohol, reweigh.
Added 5.12 mL of isopentyl alcohol.
Weight of cylinder plus alcohol = 12.438 g
Weight of alcohol = 12.438 g - 8.687 g = 3.751 g
Calculations:
Always use the correct number of significant figures in your calculations. Show work for all
calculations.
Conclusion:
The conclusion should briefly restate the objective of the experiment. Did you achieve the objective of
the experiment? What data supports the conclusion? Based on the results you obtain, briefly state the
conclusions you can reach. Be sure that you cite the specific experimental result(s) you obtained that
supports each conclusion. Be sure your conclusions use the results on any graphs, spectra,
chromatographs etc. Finally, discuss any problems and/or errors you experienced which might have
impacted your results.
Avoid unsubstantiated generalities, and do not overstate the conclusions. A common error is to state a
conclusion which he or she assumes or thinks is correct, rather than stating definite conclusions which
follow from specific experimental results obtained by the student. Do not state opinions here.
Two different student conclusions might read:
"The reaction gave a low yield of 50.0 %"
"The reaction gave a high yield of 50.0%.
Low or high compared to what? These are both opinions. A correct statement would contain the
percent yield, but not contain any opinions about the number. Words to avoid that often signal an
opinion include: high, low, very, great, satisfactory, unsatisfactory, well, good, and bad.
An appropriate conclusion might read:
"Isopentyl acetate was prepared from an esterification reaction of acetic acid and isopentyl alcohol. The
crude product was isolated by extraction and drying over sodium sulfate, and then purified by
distillation. 0.498 g (43.3 % yield) of pure product was obtained. Some of the purified material was lost
in the distillation apparatus because drops were clinging to the condenser and because several mL of
crude material was unable to be recovered from the flask. The pure product was a viscous, pale yellow
oil with a fruity odor. The infrared spectrum of the pure product was similar in appearance to the
spectrum of isopentyl acetate in the lab text (both major and minor peaks matched in intensity and
frequency), except the product IR showed a large water peak at ~ 3650 cm-1. For this reason, the
calculated percent yield may be high due to the presence of water in the product."
Note the following information that appears in the above conclusion:
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The conclusion states what was performed, and it mentions the methods of preparation, isolation,
and purification.
Both the grams of product and the percent yield are noted. Experimental details are mentioned
that would result in a lower yield.
Data is compared to what is expected (in this case, from the lab text). Specific details are
compared and there is no speculation.
A probable source of error is mentioned and its consequences discussed.
A bad conclusion might read:
"The lab went fairly well. We first cleaned our glassware and then followed all of the procedures. We
got a 43.297351403 % yield which is similar to what the group next to us got. I suspect that our yield
was too low because I couldn't get all of the liquid out of the flask, plus we saw some powder around the
scale when we were weighing out our starting material which we think was because we spilled a little.
Despite this, when we took a spectrum of our product it clearly showed we were successful. Overall, the
lab was a good one."