General Chemistry Laboratory
Guidelines for Writing the Post-laboratory Report

Format and Content:

• Your name
• Partner name when appropriate
• TA name
• Date
• Experiment title

Introduction: The report should begin with a brief introduction of the subject matter and why it is of interest. Describe the underlying theory if appropriate. The introduction should also include a statement of the problem addressed by the laboratory experiment. In other words, describe what were you trying to accomplish by doing this experiment. (Don't simply rewrite the purpose.) Also report how you went about addressing this problem. Do not repeat the procedure. Rather, briefly describe the general technique(s) and the principle behind the technique(s) if appropriate.

Experimental: All relevant data and experimental results should be tabulated and discussed in the text of the report. Results of calculations can be included in data tables where appropriate or may be tabulated separately. Sample calculations must also be shown. (Calculations may be easily typed using the equation editor of your word processing program.)

Discussion and Conclusion: The lab text frequently provides suggested discussion questions. The following topics may be addressed in these questions, but if not, should always be considered when writing the report.

What do the experimental results tell you about the problem being addressed? Reflect back to your introductory statement and purpose. Did the lab accomplish what it set out to do? Why or why not?

Also consider the limitations of your results:

Comment on what you have learned and what information the data reveal. Consider the big picture and discuss how the techniques used or knowledge gained could be applied to other situations.

Grammar and Style:

• Be brief. Wordiness generally adds nothing but confusion and detracts from your report.
• Tense: Report experimental observations and results using the past tense. The properties of substances are reported in the present tense. Never use the future tense.
• Incorrect: A plot of volume versus temperature will yield an x-intercept of absolute zero.
• Correct: A plot of volume versus temperature yielded an x-intercept of absolute zero.
• Voice: Use the first person active voice where appropriate.
  • Poor: It was determined from the data that...
  • Better: I determined from the data that...
• Phrases such as "I believe..." or "We concluded..." are unnecessary, as are personal opinions.
• Units of measurement are treated as collective nouns and take singular subject.
• Incorrect: Five grams of NaCl were added to the solution.
• Correct: Five grams of NaCl was added to the solution.
• Every table must have a brief title that describes its contents. Every column must have a heading that describes the material below it.
• Graphs should fill a full page and be drawn according to the guidelines in the laboratory text.
• All tables and graphs should be keyed into the text and sufficiently discussed.

• Always use complete sentences.
• Proofread.
• Remember that spelling counts. Use a dictionary or the spell checker on your word processing program.
• Never report numbers without units.

A sample lab report is available. Because every laboratory experiment is different, this sample report should be regarded as a guideline for how a report should be written, rather than a template to be followed exactly.