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, concise, and well organized and
should make effective use of tables and graphs.
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 8 pages
(not counting attachments) applies to all lab reports.
(Please number the pages!)
- 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 (especially in your
results tables) 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.
Title Page
- Give the number and title of
the experiment, your name, course number and section,
and the date submitted.
Results Tables (The
results tables can either be grouped all together in
their own separate section or they can be interspersed
where appropriate throughout the Results and
Discussion.)
- 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 the structures of
the compounds listed in the tables either within
the table or or elsewhere on the same page.
- Include the 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 (mp, bp, refractive
index).
- Indicate units where required.
(A well-organized table gives the units in the column
headings rather than repeatedly throughout the table.)
- Make sure to observe the
significant figures convention!
- Use footnotes as necessary to
fill in missing details or to give definitions of any
non-standard abbreviations used in the table.
- Spectroscopic Results
- Include tables that
summarize the spectra obtained. These tables should
list all peaks
observed and their key characteristics.
- MS. Round
peak m/z values to the nearest whole
number. List the approximate percent abundance
of each peak (as compared to the base peak).
- C-13
NMR. Round peak shifts to the nearest
0.1 ppm except when greater precision is
needed to distinguish closely spaced peaks.
- H-1 NMR. Round
off peak shifts to the nearest 0.01 ppm. Make sure to also
state the multiplicity and integration value of
each peak.
- Always 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 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
- Do not include solvent peaks
(e.g., H2O, CDCl3) in NMR
tables.
- Include literature values
(i.e., chemical shifts and m/z
values). Use a superscript number to cite the
reference. (See the part on references below)
Results and
Discussion (R&D)
- This section is referred to as
"Results and Discussion" because the proper way to go
about it is to state some results and then go on to
discuss them.
- Make sure to actually state
the results to be discussed rather than just refer to
a table. For example, even though your Table 1 might
show the observed and literature mps for your product,
your R&D part should start out as, "The mp of the
product was found to be XX in comparison to the
literature value of XX. (Table 1)"
- After stating the results, go
on to explain your interpretation as to how they align
with the theory behind the experiment.
- 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.
- Spectra
Interpretation - Evidence for the
structure of the product from NMR, MS, 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.
References
- Give sources for all
literature values as well as for any other background
information included.
- List the references in the
order they are cited in the report.
- Give each reference its own
number (in parentheses). Use these numbers in
superscript form to cite the appropriate reference
throughout the report. (For example, in the results
table the references for the literature values should
be given.)
- Use ACS style for your
references list. See http://courses.chem.psu.edu/chem431/ManuscriptFiles/QuickRefGuide2.pdf
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). Label all peaks on the NMR
spectra. By labeling all solvent peaks and other
expected extraneous peaks (e.g., TMS, water) you
make clear what they are without unnecessarily
devoting lab report discussion to them. For IR and
Mass spectra it is not necessary to label small
unidentifiable peaks especially those in the
fingerprint region of the IR.
Product Submission
- Products are ordinarily
submitted for grading and then proper disposal.
Submitted products should placed in screw-top vials (not conical vials or
reaction flasks) and fully labeled with the compound
name and structure, your name, experiment number, and
course number.
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