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Guidelines
for Lab Reports
Learning how
to effectively report experimental results is extremely
important in all of the sciences. Although the customary
format may vary between discipline, a scientific report
should be clear, thorough, concise and well organized
and should make effective use of tables and graphs.
General
Guidelines
Formatting
- Reports should be
word-processed and double-spaced.
- Do not ignore the need
for subscripts and superscripts in chemical formulas.
These are easily available in all modern word
processors.
- Use a minimum font size
of 11 and left and right page margins of 1.0".
Conciseness
- Strive to make your
report as concise as possible. A page limit of 12
pages (not counting attachments) applies to all lab
reports. (Please number the pages!)
- In achieving
conciseness, it is important that you use standard
abbreviations and/or chemical formulas where possible
in place of full chemical names. For example write
"MeOH" instead of "methanol" and CDCl3
instead of chloroform-d.
- All measurement units
have standard abbreviations and these should always be
used in conjunction with the numerical value for the
measurement, e.g. always write "15 cm" not "15
centimeters" or "fifteen centimeters".
- Here is a spreadsheet with
commonly needed standard abbreviations. Remember to
use these freely and to not waste space defining them.
- Also
consider creating your own abbreviations to replace
long compound names. Define these simply by placing
parentheses immediately after the first instance of
the full compound name in the report.
Data
Interpretation
- Students are encouraged to bring
rough drafts and questions about data interpretation
to the instructor prior to submitting their final
report. (Unless otherwise announced in lab.)
Organization
Title Page
- Give the number and
title of the experiment, your name, course number and
section, and the date submitted.
Purpose
- Give specific
information on the reaction being carried out
including chemical equations showing structures of all
reactants and products.
Mechanism
- Present and
discuss the accepted mechanism for the
reaction carried out. Make sure to use
equations/structures/curved arrows as necessary to
show the mechanism properly.
Results Tables
- Present all of the
results of the experiment in table form.
- Try to make your
results tables as concise and well organized as
possible.
- Number and
title your tables. The title should give fairly
complete information about the data contained in
the table.
- Include
structures of the compounds in the tables.
- Include the absolute
yield (mass), theoretical yield, and percent yield
(rounded to the nearest whole number) of any product
obtained. (Show the calculation of theoretical and
percent yield on an attachment.)
- A melting point range
should be reported for every crystalline solid
product.
- Include literature
values for any physical constants measured.
- Make sure to give units
where required. (A well-organized table gives the
units in the column headings rather than repeatedly
throughout the table.)
- Also include
summaries (i.e., peak listings) of any spectroscopic
data (NMR, IR, MS) obtained.
- Round off IR
frequencies to the nearest 1 cm-1 and
MS peaks to the nearest 1 m/z unit. Carbon NMR
peak shifts should be rounded off to the nearest
0.1 ppm except when greater precision is needed
to distinguish closely spaced peaks. (These
guidelines are taken verbatim from the Journal of Organic
Chemistry's guidelines for authors.)
- Do not include
solvent peaks (e.g., CDCl3) in NMR
tables.
- Do include
literature values of chemical shifts, wavenumbers,
and m/z when available.
- For NMR, IR and
MS tables you should include a column for "peak
assignment".
- For NMR the
assignment should be a letter that refers to a
labeled chemical structure included with the
table.
- For IR the
assignment should refer to the specific type of
bond vibration and the functional group family,
e.g., C=O (ketone), C=O (anhydride), O-H
(alcohol).
- For MS, the
assignment can take form of describing the
neutral fragment lost, e.g. M - CH3,
M - Br, or preferably show the structure of the
cation detected
- Make sure to
observe the significant figures convention! Significant
Figures Tutorial
- Use footnotes as
necessary to fill in missing details or to give
definitions of abbreviations used in the table.
- Also use footnotes
to give references for literature values. (Refer to each reference
by its number in your report-end
list of references. For example a table
footnote might typically read, "See
reference 3.")
Results
and Discussion
- Start by presenting key
results from the results tables briefly in a
non-interpretive way. Point out the most important
take-home points from the table and/or any trends you
would like to draw attention to.
- Go on to explain your
interpretation of these results. Your main aim is to
show how they support the theories presented in the
background.
- Make liberal use of
structural diagrams, equations, curved arrows, images
of molecular models, etc., to illustrate points being
made as appropriate.
- For puzzling results
that do not seem to fit the theoretical expectations,
are there valid explanations for them? Are they
erroneous (due to systematic experimental error)
(identify the specific reason for the systematic error
if you think it is present). If you can rule out
systematic error then examine how the theories could
be modified to accommodate the results.
- This section should
include answers to the assigned questions. Make sure
to explain all answers completely even if the question
does not ask for an explanation.
- Above all, make sure
your answers and interpretations make sense! Do not
just take a stab at interpreting the results! If
uncertain, do some Internet and/or library research or
ask the instructor if you are on the right track.
- For synthesis
experiments always discuss:
- Yield
- Actual yield of product versus the theoretical
yield (percent yields) and possible reasons for
loss of yield. Please see this page for more info:
Yield Reporting and
Discussion
- Spectra
Interpretation - Evidence for the
structure of the product from NMR, IR and/or
chemical tests.
- Purity
- Purity of the product as indicated by mp, bp,
NMR, etc. Identify impurities that are
present if possible, explaining thoroughly the
reasoning behind your conclusions.
Summary
- Reiterate the main
points from your results and discussion sections in
very brief form. Ideally, you can boil down the
experiment to four or five main conclusions, each
stated in one or two sentences.
- Give actual data again
in this section to support each conclusion. The data
can be concisely included simply by providing it in
parentheses at the appropriate places within the text.
- Comment on whether the
experiment was successful or not and feel free to make
suggestions as to how the experiment could have been
better designed or carried out.
References
Attachments
-
Calculations - An
example of each non-trivial calculation, including %
and theoretical yield calculations,
should be shown. Do not include trivial
calculations such as subtraction of tare weights.
-
Spectra - Attach
printouts of all spectra obtained. Make sure
the spectra are completely labeled (name, date
section number, expt number and title). All
peaks should always be labeled. By labeling all
solvent peaks and other expected extraneous peaks
(e.g., TMS, water, CHCl3) you make clear what they
are without unnecessarily devoting lab report
discussion to them.
Product Submission
- Products are ordinarily
submitted for grading and then proper disposal.
Submitted products should be fully labeled with the
compound name and structure, your name, experiment
number, and course number.
- Solid products should
be placed in small 2"x2" zip-lock baggies.
- Liquid products should
be placed in screw-top vials (not conical vials or
reaction flasks).
Team Contribution
Surveys (TCSs)
- These are made
available on D2L the same day the lab report is due
for each experiment. They are due within one week of
the lab report submission.
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