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Chemistry 247 + 347 + 348: Writing your Lab Report

This guide is for Dr. Montserrat Rabago-Smith's chemistry classes

The Voice of Writing

"Voice" refers to the way the verb is used in the sentence. Remember that a sentence has to have a subject and a verb, and many verbs require direct objects. Below are two examples one of a passive voice and the other of an active voice.

Here is an example of an active voice:


In passive voice, the subject of the sentence also receives the action. The doer of the action is someone else. Here’s an example of passive voice:



We write lab reports in passive voice because:

It’s part of the scientific point of view.  We observe and record as objectively as possible, avoiding personal bias by removing ourselves.  Using the passive voice also clarifies procedures and descriptions so they can be easily reproduced and compared.

NOTE: DO NOT write reports as directions, such as those given in your lab manual. For example, do not write, "Heat the solution until it boils." Instead, write "The solution was heated to boiling."

Examples of a passive voice in lab reports


200mL of distilled water was poured into a 500 mL beaker.


I poured 200mL of distilled water in a beaker. (active voice)

Pour 200mL water in a beaker. (direction/command)


The covered crucible was mounted on a ring stand.


We put the crucible on a ring stand. (active voice)

Set the crucible on a ring stand. (direction/command)


The temperature was initially measured at 75°C.


I measured the temperature at 75°C. (active voice)

Measure and write down the temperature. (direction/command)

It's understood that all actions were done by the experimenter.


Whether you are filling out lab worksheets or writing up entire lab reports, there are a few tips that will help you to create more detailed and professional documents and to assist in grading:

  • Always label your units
  • Show all of your calculations (don’t leave out steps)
  • Use complete sentences
  • Write neatly
  • Strike out mistakes with a single line
  • Be aware of significant figures, noting the sensitivity of the device you are using for your measurements

‚ÄčWrite in the third person - Scientific experiments demonstrate facts that do not depend on the observer, therefore, reports should avoid using the first and second person (I,me,my,we,our, OR us.)

Using the correct verb tense - Lab reports and research papers should be mainly written in the present tense. You should limit the use of the past tense to (1) describe specific experimental methods and observations, and (2) citing results published in the past.

Tables and Figures - Should be used when they are a more efficient ways to convey information than verbal description. They must be independent units, accompanied by explanatory captions that allow them to be understood by someone who has not read the text.

Example of a Good and Bad Lab Report

Information is from Purdue University's Chemistry Lab Resources Guide

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