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Writing Laboratory Reports for Chemistry Experiments Tutorial

Key Concepts

Heading Information contained in this section
Title : Name your lab report so people can refer to your work.

Introduction : Explain why you did this experiment.

Discuss what you expected to find by doing this experiment.

Materials and Method : Describe how you performed the experiment.

Results and Discussion : Describe what you found out by doing the experiment (results).

Discuss how you interpreted the results of your experiment.

Discuss the implications of the conclusion you made about the results of this experiment.

References : Write bibliographic information for every source you cited in the lab report.

Note: different courses have different requirements for the presentation of Lab Reports.

Your teacher will provide you with the details of what is expected from you in your Lab Reports.
Read these instructions carefully BEFORE you begin to write your Lab Report!
If you do not understand an instruction, ask your teacher to explain it to you.

The following discussion is about the features that will be common to ALL Lab Reports.

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Lab Reports are Written with Scientific Integrity

You must truthfully record the results of your experiment.

You must not change the results of your experiment because you think they are wrong, or because they don't agree with the textbook, or because you spilled some of the reactant and didn't go back and measure it again, or for any other reason!

If the results of your experiment do not agree with published results, for example data in a textbook, then you can try to explain why in the discussion section of your lab report.
If you spilled some product of a reaction before you had a chance to weigh it, then, in an ideal world, you would have to discard this part of the experiment and start again.
In the real world of the school laboratory you probably won't have time to re-do the experiment, so you will have to explain the impact of this loss on your results in the discussion section of your lab report.

There are many examples in the history of Chemistry in which a Chemist got strange results, but, instead of changing the results to what was expected, the Chemist truthfully recorded the results so that the whole scientific community could investigate the strange results.

In fact, the 2011 Nobel Prize in Chemistry was awarded to a man because he didn't falsify his data so that it would agree with the scientific theory current at the time, instead, he spent years trying to convince other scientists that the theory was wrong because his data was good. Scientists opposed the "correctness" of his data so much that he even lost his job. Eventually, however, other Chemists reproduced his results, and the evidence became so overwhelming that a complete revision of the scientific theory was necessary!(1)

So the moral of the story is that you MUST NOT falsify your results, you never know what you might miss out on if you do!(2)

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Scientific Language Used in Lab Reports

The focus of a lab report is the science, not you!

For this reason, lab reports are written in the third person passive style.

A quick grammar lesson for chemistry students: What does third person passive style mean?

Compare the following examples of language below:
First person active: talking about yourself or others doing something by using the words I, me, my, mine, we, us, our Example: I poured 10 mL of water into a 100 mL beaker.
Example: We poured 10 mL of water into a 100 mL beaker.
Third person active: removes reference to specific people by name or pronoun Example: The author poured 10 mL of water into a 100 mL beaker.
Third person passive: completely removes reference to people Example: 10 mL of water was poured into a 100 mL beaker.

So, third person passive simply means that the people who perfomed the experiment are not referred to in the Lab Report.

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Components of the Lab Report (Sections of the Lab Report)

The purpose of the lab report is to provide other people with enough information about the experiment so that they can reproduce the experiment and get the same results.
The general form of the lab report you will be required to write in High School is no different to the general form used by professional Chemists to report their findings to the scientific community in scientific journals.

The components that are common to all lab reports, and in the order in which they are written, are:

  1. Title
  2. Introduction
  3. Materials and Methods
  4. Results and Discussion
  5. References

Your completed Lab Report will have a number of different sections. Each section, except the title, will have a heading. The heading of each section will be the name of one of the components listed above.

(a) Title

The title of your lab report should be:

Think of the names (titles) of the best movies you have ever seen. What are the things that all those names (titles) have in common?

You want people to read your lab report, so just like a movie title, you need a short, informative, interesting title.

Example: In an experiment in your laboratory you measured the temperature of 10 mL of water in a 50 mL beaker. You then added 10 grams of ice to the water and measured the temperature of the water every minute until all the ice had melted and the beaker contained only liquid water.
The experiment was about finding how the temperature of water changed as the ice melted, so the key words to include in the title are temperature, water and ice.
A suitable title for the lab report might be, "Effect of Melting Ice on Water Temperature", or, "Temperature of an Ice-Water System".
It's probably advisable to avoid humorous titles, what you think is funny might not seem funny to someone else (you could even offend someone with your "humorous" title).(3)

(b) Introduction

The introduction is your chance to tell the reader why you did the experiment.
(and the reason is NOT because your teacher said you had to!)
Experiments are designed to answer, or at least to investigate, scientific questions.
The introduction to your Lab Report must tell the reader what scientific question you are trying to answer (or investigate).

(c) Materials and Methods (or Procedures)

This section of your Lab Report must include enough information so that someone else can follow the directions in order to replicate the experiment and get the same results.

Keep it brief!

So far, your lab report will have the sections:


(Introduction if you are required to design and perform an experiment yourself, with the heading Introduction)

Aim (goal or objective, with the heading Aim)

Materials (with the heading Materials)

(Hazards if required with the heading Hazards)

Method (or procedure, with the heading Method or Procedure)

Results and Discussion

Results are presented first, followed by the Discussion.

So far, your lab report will have the sections:


(Introduction if you are required to design and perform an experiment yourself, with the heading Introduction)

Aim (goal or objective, with the heading Aim)

Materials (with the heading Materials)

(Hazards if required, with the heading Hazards)

Method (procedure, with the heading Method or Procedure)

Discussion (with the heading Discussion)

(Conclusion if required, with the heading Conclusion)


The source of any information you have used (actually cited) in your Lab Report must be written down in the reference section.
This enables someone who is interested in your experiment to look up the information for themselves.

If you have copied any text word-for-word from someone else's work, you must cite this in-text (that is, where it occurs in your Lab Report) by placing quotation marks around "the text" and by placing the referencing information inside (brackets) or by adding a footnote (depending on the instructions you have been given), and then add the full bibliographic information for this source in your Reference section.
Similarly, if you have copied any diagrams you will need to reference those.

There is more than one way to cite and reference sources.
You teacher will provide you with the details of how you are to cite and reference sources in your Lab Report.

Your completed lab report will have the sections:


(Introduction if you are required to design and perform an experiment yourself, with the heading Introduction)

Aim (goal or objective, with the heading Aim)

Materials (with the heading Materials)

(Hazards if required, with the heading Hazards)

Method (procedure, with the heading Method or Procedure)

Discussion (with the heading Discussion)

(Conclusion if required, with the heading Conclusion)

References (with the heading References)

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Checklist : Have you missed anything in your written lab report?

Before submitting your Lab Report for marking, check that you have:

followed all the instructions your teacher gave you (including the date your lab report is due!)

all the headings and sections you are required to have

used the third person passive throughout the Lab Report

cited all the sources you used

given the bibliographic details for all the sources you cited in the Lab Report

identified the Lab Report as your own

(did you need to include a Title page with your name on it? with the date on it? with your teacher's name on it? etc)

If this is a major assessible project, then, when you are satisfied that your Lab Report fulfills all the requirements, you should do 2 things:

  1. Make a copy of the completed Lab Report before you submit it.
  2. Keep the copy in a safe place!

Why should you make a copy?
Because it takes a long time to write a good Lab Report. If the original is, for any reason, misplaced, you will always have the copy to re-submit!

The best example I know of for why you should make a copy of anything that is important comes from the world of Mathematics (Number Theory).
In 1637, Pierre de Fermat wrote, in the margin of a book, that he had found a proof for the conjecture that no three positive integers can be found that will satisy the equation

an + bn = cn

for n > 2

but, that the proof was too large to fit in the margin.
Since he didn't keep, or indeed publish, this proof, it was lost to the world, until Andrew Wiles successfully proved it in 1995.(4)
If Fermat had kept a copy of the proof and published it, Mathematicians could have devoted more than 350 years to other useful research, and who knows how far advanced mathematics would be now!


(1) Dan Shechtman first noted a "forbidden symmetry" in crystals in 1982 (forbidden by the prevailing theory at the time). No scientific journal would be prepared to publish his results until 1984. It wasn't until 1992 that the International Union of Crystallography was convinced enough to change the official definition of a crystal!
You can read more about this discovery in the December 2011 AUS-e-NEWS.

(2) Unfortunately the history of science also includes the names of people who did falsify results, or at the very least did not practise good scientific technique, or of those who were, at best, self-delusional.
Rather than provide examples of "poor science", why don't you read one of the many interesting books available about this?
I'm rather fond of "Bad Science" written by Ben Goldacre and published by HarperCollins Publishers in 2009, and I also like "Sorting the Beef from the Bull: The science of food fraud forensics" by Richard Evershed and Nicola Temple, published by Bloomsbury Publishing in 2017.

(3) Yes, OK, you caught me out! One of the reasons I LOVE the book, "Sorting the Beef from the Bull", cited above is because of the title which I find to be both clever and amusing. If you don't find the title humorous that's OK, ignore the title and enjoy reading the book anyway.

(4) If you happen to be a clever mathematician you can read the proof in the May 1995 issue of "Annals of Mathematics".
If, like me, you would prefer to read an account of how the proof came about, try reading "Fermat's Last Theorem: Unlocking the secret of an ancient mathematical problem" by Amir D. Aczel available in Penguin Books (1997).