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!)
• In achieving conciseness, one can use standard abbreviations and/or chemical formulas (when unambiguous) 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 (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! Significant Figures Tutorial
• 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 (NMR, IR, MS). These tables should list all peaks observed and their key characteristics.
  
• IR. Round peak frequencies to the nearest 1 cm^-1. Describe each peak as vs (very strong), s (strong), m (medium), w (weak)
  
• 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 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
• Do not include solvent peaks (e.g., H₂O, CDCl₃) in NMR tables.
• Do include literature values of chemical shifts, wavenumbers, and m/z when available. 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. 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.

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 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.