How to Write a Laboratory Notebook
Notebook Format - General
The laboratory notebook should be a complete record of the experimental work. The
criterion used in judging what should be in the notebook is that the record should be so
thorough and so well organized that another student who reads the report can understand
it, can see exactly what has been done, and can repeat the experiment, if necessary, in
precisely the same way the original work was done.
All data are to be recorded in the notebook in ink, at the time they are obtained.
There is no reason for recording anything on scratch paper to be transferred into the
notebook later. If a mistake is made in the notebook, simply cross out the error and make
the correct entry next to it. Neatness is desirable, but it is much less important than
completeness.
Use the following general format for setting up your notebook:
- Leave a few pages at the beginning of the notebook for a Table of Contents. Keep the
Table up to date.
- If the pages are not already numbered, number them. All consecutive pages must remain in
the notebook; do not remove any pages. If you really mess up a page, draw a diagonal line
through it and start over on a new page.
- Start every new experiment on a fresh page. If you have two experiments active at the
same time, leave enough pages between them in the notebook; any unused pages or portions
of pages at the end of an experiment should have a diagonal line drawn through them.
- It is not necessary to copy the details of an experimental procedure, provided you
reference the source of the procedure. However, any variations from the original procedure
must be documented in the notebook. Remember, your notebook should be a log of your
laboratory operations; someone should be able to reconstruct later just what was done and
why it was done. Never delete anything-draw a line through it and amend it appropriately.
What you consider wrong at one time might turn out to be right later.
In organic chemistry lab there are generally two different kinds of experiments: the
"preparative" type in which you carry out some sort of synthesis or conversion,
and the "investigative" type where you study or measure some physical or
chemical property. As an aid in preparing your notebook, two slightly different formats
for these types of experiments are suggested below. Feel free to adjust the format to a
given experiment as the need arises; any major deviations from these will be discussed in
lab lecture.
Format for Preparative Experiments
Before coming to lab (must be checked by instructor before you can start)...
- Title: Title of experiment.
- Purpose: A brief statement of the experimental objectives.
- Reactions and Mechanisms: Give the main chemical reaction(s) leading to the
product; where feasible, include the mechanisms of the reactions and possible side
reactions that could diminish the yield of desired product.
- Reference: Bibliographic citation of the experimental procedure.
- Procedure: Original procedure or deviations from referenced procedure.
- Table of Reagents and Products: List in tabular form the physical properties of
each reactant, reagent, solvent, and product, including molecular weight, melting or
boiling point, density, and other properties where applicable. The "CRC
Handbook" and the "Merck Index" will be your major sources for this
information. Also note any particular hazards associated with the use of the reagents.
- Calculations: Calculate the molar, and mass or volume, amounts of each of the
reagents and include these in the table; calculate the limiting reactant and the
theoretical yield of the product.
- Prelab Questions: While normally not part of a laboratory notebook, you
may wish to put the answers to the prelab questions in your notebook since the prelab
quizzes may from time to time be based on the prelab questions.
In lab...
- Observations and Data: Observations, particularly those that were unanticipated;
any changes in experimental procedure not documented above; and raw data and results are
to be recorded directly into the notebook during the laboratory exercise.
After lab...
- Results: Actual yield; percent yield; measured physical properties of the product
-- mp, bp, color, purity, spectroscopic data as appropriate, etc.
- Discussion and Conclusion: Discussion of the results, particularly if they were
not what was expected or if yield was too low or too high; significant conclusions. If an
electronic report is available, the Discussion and Conclusion need not be included in the
lab notebook.
Format for Investigative Experiments
Similar to the above format but with the following modifications:
- Title:
- Purpose:
- Reference:
- Procedure:
- Table of Reagents: (where applicable)
- Prelab Questions:
- Observations and Data:
- Results: Calculations based on raw data; calculation of experimental error;
summary of experimental results.
- Discussion and Conclusion: Discussion of the results, their validity or accuracy;
experimental errors; significant conclusions based on your results. If an electronic
report is available, the Discussion and Conclusion need not be included in the lab
notebook.
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