Guidelines for Writing a Lab Report

Guidelines for Writing a Laboratory Report
Quinetta D. Shelby
(last update on 8/14/09)

Adapted from The ACS Style Guide: Effective Communication of Scientific Information, 3rd Edition; Coghill, A. M., Garson, L. R., Eds.; Oxford: New York, 2006.

Plagiarism Policy:

Plagiarism is not tolerated at DePaul. You should read and become familiar with the DePaul University Academic Integrity Policy (http://academicintegrity.depaul.edu/AcademicIntegrityPolicy.pdf). You should also visit the FAQs webpage (http://academicintegrity.depaul.edu/FAQ/ForStudents/index.html) for helpful information about proper citation and paraphrasing of another’s work.

Other Resources:

This document is meant to provide you with very general guidelines that are applicable in all chemistry courses. Please refer to information from your laboratory instructor for more specific expectations regarding report writing.

General notes:

One of the best ways to improve your writing is to review your report before you submit it! You can often find and easily correct many mistakes when you read your own writing.

If a human did it, then use past tense. If the molecule or spectrum does it, or if it is a statement of fact, then use present tense.

There is no such thing as an average melting point (boiling point). Your first measurement gives you the approximate Mp (Bp), and your second measurement (taken at a slower temperature climb) gives you the more accurate Mp (Bp). Report the better Mp(s) (Bp(s)), but do not average them.

If you can count them, then use the word “number,” and if you cannot count them, then use the word “amount.”

Report the percentage yield/recovery of your experiment in your Abstract. Provide the actual grams and the percentage in the Results and/or Experimental section. Your reader does not know if 3.00 g of compound is terrific or terrible if that is all the information you provide.

Your data supports your conclusions, but your conclusions do not support the data.
X - The strong band at 1623 cm^-1 appears in the IR spectrum because the compound has a carbonyl group.
√ - The strong band at 1623 cm^-1 in the IR spectrum indicates that the compound has a carbonyl group.

Your IR and NMR data do not appear in a graph, they appear in a spectrum. Also, it is okay to say, “the NMR/IR contains,” but it is not okay to write this. You must include spectrum when you write.
X - The NMR graph contains four signals.
√ - The NMR spectrum contains four signals.
X - The IR contains a broad hydroxyl peak at 3620 cm^-1.
√ - The IR spectrum contains a broad hydroxyl peak at 3620 cm^-1.

Do not use “once” when you really mean “after.”
X - The mixture was filtered once crystals formed.
√ - The mixture was filtered after crystals formed.

Do not use “since” when you really mean “because.”
X - The compound is probably a carboxylic acid since its IR spectrum contains –OH and C=O stretches.
√ - The compound is probably a carboxylic acid because its IR spectrum contains –OH and C=O stretches.

Do not use “about” when you really mean “approximately.” In most cases, it is acceptable to just state a numerical value rather than an estimation.
X - The reaction mixture was stirred for about 30 minutes.
√ - The reaction mixture was stirred for approximately 30 minutes.
√+ - The reaction mixture was stirred for 30 minutes.

Technically, you cannot do/perform the reaction, only the compounds can. You can conduct/run/study the reaction, you can perform the experiment/study, and you can add/treat/mix/combine the compounds.
X - The alkyl halide was reacted with NaOH to form an alcohol.
√ - The alkyl halide reacts with NaOH to form an alcohol.
√ - The alkyl halide was mixed with NaOH to form an alcohol.

The word "filtrate" is a noun, not a verb.
X - The mixture was filtrated.
√ - The mixture was filtered.

Do not use the word "off" unnecessarily in your written report.
X - The solvent was evaporated off.
√ - The solvent was evaporated.
X - The unknown was identified as toluene based off of its boiling point and spectroscopic data.
√ - The unknown was identified as toluene based on its boiling point and spectroscopic data.

Although it is acceptable to use "I" or "we" in your report, you should avoid doing so (more than once in a typical report is too many). Reword the sentence to avoid this, besides, actions completed by you should be in the passive voice.
X - I refluxed the reaction solution for 1 hour.
√ - The reaction solution was refluxed for 1 hour.

Do not start a sentence with a number.
X - 18 g of H₂O (1 mol) was added slowly to the reaction solution.
√ - H₂O (18 g, 1 mol) was added slowly to the reaction solution.

Title:

The title should concisely describe the content of your laboratory report.

Abstract:

The reader should be able to get the gist of your lab report from your abstract. In a nutshell, the abstract should describe what you did (the experiment, reaction type, reagents, reaction conditions, characterization), what you got (key results, percentage yield, melting/boiling point, key spectroscopic data), and what you think (conclusions based on your results). The abstract could be only a couple sentences, but it must be no longer than one paragraph. Write the abstract after you have written the other sections of your report. The abstract should not contain references, tables or figures.

Examples
Inorganic
Organic

Introduction:

The introduction should briefly describe the interest in and the purpose of the experiment. You should give background information on what is already known about the compound (or class of compounds), the reaction procedure or the analytical technique. You should connect the background to the objective of the experiment, but avoid detailing your results in this section. Also, include reaction equations in the introduction section, if appropriate.

Examples
Inorganic
Organic

Experimental:

The experimental section details what you did (long version). The details required in this section depend on the course so refer to the lab course syllabus. In some cases, you will only cite the experimental source and only detail experimental changes or additional information not provided in the original procedure. In other cases, you will need to provide a step-by-step procedure in your own words that another researcher can follow and obtain similar results.

Examples
Inorganic
Organic

Results:

The results section details what you got (the long version). Only include key results that support your conclusions. Even if you use tables to present your data, you need to write sentences that help the reader to understand the importance of the data. Also, include reaction equations in the results section, if appropriate.

All tables and figures must be mentioned in the text of the report, and they must be numbered consecutively. Tables and figures must have titles, and tables must have descriptive column headings. If you provide a table of IR or NMR spectroscopic data with assignments, then you do not need to label the bands or signals on the spectrum, but you still need to attach the spectrum to your report.

Examples
Inorganic (with tables)
Organic
Figures - GC/MS, IR, ¹H NMR

Discussion:

The discussion section details what you think (the long version). You should directly address the goal of the experiment that you described in the introduction. Analyze your data and explain how it leads to your conclusion(s). Spell this out for your reader; your reader should not have to interpret your data and justify your conclusions. Here, you can also mention major procedural/technical errors. For example, if everyone got 75% yield and you got 65%, then do not discuss it. However, if your yield was half of everyone else’s (~40%), then discuss it. To avoid redundancy, some people combine the Results and Discussion sections; refer to the guidelines provided in your lab course syllabus to write these sections according to your instructor’s expectations.

Examples
Inorganic (with tables)
Organic

Calculations:

Refer to the guidelines provided in your lab course syllabus and/or experimental procedure for information on the expectations regarding calculations.

References:

The minimum number of references required depends on the lab course. Refer to the course syllabus for information on this.

At the undergraduate level, most of your reference sources will be books, journal periodicals, and websites.
You can use web sources that end in .edu, .gov, or .org. Generally, only .com chemical company sources will be accepted. The wikipedia.com website is not an appropriate information source for your lab report. Because this site is the “free encyclopedia that anyone can edit,” information found through its website may not be based on data accepted by scientific community.

The following reference guidelines are from the ACS Style Guide.

Books without editors
Author 1; Author 2; Author 3; etc. Chapter Title. Book Title, Edition Number; Series Information (if any); Publisher: Place of Publication, Year; Volume Number, Pagination.
or
Author 1; Author 2; Author 3; etc. Book Title; Series Information (if any); Publisher: Place of Publication, Year; Volume Number, Pagination.

Example: Lehman, J. W. Multiscale Operational Organic Chemistry: A Problem-solving Approach to the Laboratory Course; Prentice Hall, Inc.: New Jersey, 2002; pp. 35-39.

Books with editors
Author 1; Author 2; Author 3; etc. Chapter Title. In Book Title, Edition Number; Editor 1, Editor 2, etc., Eds.; Series Information (if any); Publisher: Place of Publication, Year; Volume Number, Pagination.
or
Author 1; Author 2; Author 3; etc. In Book Title, Edition Number; Editor 1, Editor 2, etc., Eds.; Series Information (if any); Publisher: Place of Publication, Year; Volume Number, Pagination.

Example: Dodd, J. S.; Solla, L.; Bérard, P. M. References. In The ACS Style Guide: Effective Communication of Scientific Information, 3rd Edition; Coghill, A. M., Garson, L. R., Eds.; Oxford: New York, 2006; pp 287-327.

Journal article with title
Author 1; Author 2; Author 3; etc. Title of Article. Journal Abbreviation Year, Volume, Inclusive Pagination.

Example: Bielawski, C. W.; Benitez, D.; Grubbs, R. H. Synthesis of Cyclic Polybutadiene via Ring Opening Metathesis Polymerization: The Importance of Removing Trace Linear Contaminants. J. Am. Chem. Soc., 2003, 125, 8424-8425.

General web sites
Author (if any). Title of Site. URL (accessed Month Day, Year), other identifying information (if any).

Example: Benzaldehyde. http://webbook.nist.gov/cgi/cbook.cgi?ID=C100527&Units=SI&Type=IR-SPEC&Index=1#IR-SPEC (accessed June 10, 2009).