How to Write AP® Chemistry Lab Report
Labs are an important part of what you learn in AP® science classes and knowing how to write an AP Chemistry lab report is a skill that will serve you well not only on the AP Chemistry exam but in helping you think like a scientist. Why does this matter? Well, scientists must be able to communicate their findings to other scientists, and lab reports are one way in which to accomplish this.
Writing a good lab report starts with taking smart steps when you conduct the lab. You should take notes about your methods, keep careful track of your data, and think critically during the lab about what could have been improved or done differently. If you are allowed to, taking pictures of your experimental setup is a good idea to make sure you are accurate in your descriptions when you write your lab report for your AP Chemistry class. If photos are not allowed, consider making sketches in your lab notebook of any complicated setups. Don’t wait too long after you perform the lab to write the lab report, so that the information is still fresh in your mind.
Individual teachers vary in their specific requirements for AP Chemistry lab report formats, so make sure you pay attention to the instructions your teacher gives you. If you have any questions or if there is something you don’t understand, ask your teacher! They are there to help you. After you write your lab report, it is important to read over it and check for spelling or grammatical errors, which are not acceptable in scientific writing. Note that with the exception of the title and materials list, you should always use complete sentences in your lab report.
Below are some general guidelines on how to write an AP Chemistry lab report. With this goal in mind, a great lab report is both concise and descriptive and contains the following sections:
Title
The title of your lab report should be as specific as possible (ie, “Lab 1” is not a specific title). Oftentimes, you can follow the model of “The Effect of X on Y.” For example, in an experiment where you tested soils with different pH levels and how well they made potato plants grow, a good title would be “The Effect of Soil pH on Growth in Potato Plants.”
You don’t need to go into too much detail in the title; that’s what the other sections are for. As an example, “The Effect of Different Soils with pH Levels of 4, 6, and 8 on Growth in 18 Potato Plants” is too much information. You should be as concise as possible while still giving your reader a good idea of what type of experiment you performed and what they should expect from the overall report.
Abstract
Although not all teachers will require an abstract, this section is good practice for reading and writing real scientific articles. This section should give a brief summary (typically less than 100 words) of the entire experiment and analysis. You should cover what is being studied, your hypothesis, and a summary of the results. You should also include a concluding statement of the big takeaways from the experiment.
Introduction/Background
This section of your lab report should provide your reader with any background information they will need to understand your experiment. You should introduce the purpose of the experiment in this section of the lab report so that it is clear why the lab experiment was performed.
In this portion of your lab report, you will state your hypothesis, or testable statement. Your hypothesis is generally written in an “If…, then…” format (eg, “If acidic soil is best for plant growth, then potato plants will grow taller when grown in soil with a lower pH”). You should include any reasoning that went into the formation of your hypothesis. For example, if you hypothesize that more acidic soil will result in better potato plant growth than more basic soil, why do you think that? Generally, you need to provide a brief definition of key terms you use in this section when they are introduced.
Materials and Methods
In this portion of your lab report, you will go into detail about the materials you used in your experiment and what steps you performed. Typically, this section involves a bulleted list of all materials used and their quantities. However, different teachers may have different preferences for how the materials you used are communicated in your lab report. Remember to include all materials you used; for example, don’t forget items such as light and water in a plant growth experiment.
In addition to the materials list, you will detail each step you took to complete your experiment. The goal of writing this section in any scientific field is to make your results reproducible by other scientists, which would make your experiment accurate and valid in the eyes of the scientific community.
Employing meticulousness in writing this section is preparing you for what to expect in the real world of science. With this in mind, make sure you mention all variables that were controlled, along with the independent and dependent variables. In addition, you should use the past tense when writing this section, as your materials and methods are a description of an experiment that you have already performed. For example, you would write “the height of each potato plant was measured daily”, not “measure the height of each potato plant daily.”
Results
The results you obtained during your experiment are displayed in this section of your lab report. Usually, this will be in the form of table(s) and/or graph(s), depending on your experiment. Think about your experiment and results, and how you can best depict them visually.
When creating tables and graphs, make sure each one is clear and easy to follow and that they each have a descriptive title. Consider whether you should include averages for experiments in which multiple trials were performed. When you display numerical figures, units should always be included. If your lab report contains a graph, make sure to label both the X and Y axes appropriately and to include a key or legend if necessary. In some labs, you will perform statistical analyses or calculations; make sure to include these here if they were part of your experiment.
The statistical analyses, graphing tasks, and tabular data production required for your AP Chemistry lab report are directly tied to the science practices you will be tested on during the AP Chemistry exam, as shown in our AP Chemistry Study Guide and Materials article. So make sure you put your best effort into learning and mastering the skill set of representing scientific data in a visual manner and using statistics-based reasoning.
Often, results that do not support your hypothesis are just as valuable as those that do. Results that do not support your hypothesis do not mean that your experiment has “failed” or that you should make up false results. So, for this section of the lab report, it is extremely important that you always represent the actual data you obtained in the experiment.
Analysis and Discussion
This section is the real meat of your lab report. Here you will present an analysis of the results you obtained in your experiment and whether they do or do not support your hypothesis. Note that this is the terminology that should be used when discussing your hypothesis in light of your results (not “prove” or “disprove”). Remember, results that do not support your hypothesis are not invalid, and this is your chance to explain why you think these unexpected results occurred.
This portion of your lab report is also an opportunity to discuss any shortcomings of the experiment, materials, or methods, and a place to provide suggestions for things that could be improved if the experiment was performed again. Additionally, you may suggest related investigations that could be performed given the results of your experiment (eg, testing different brands of soil with the same pH on potato plant growth once you arrive at the ideal pH level for potato plant growth).
You should strive to clearly explain the meaning behind your results and any implications these results have on the information discussed in your introduction/background section. You should reference your results in any statements you make about your experiment, either quoting data directly (eg, “the plants grew an average of 4.5 cm taller”) or by referencing the figure, table, or graph number (eg, “As shown in Table 1, soil at pH 4 produced greater average plant growth than soil at pH 6”).
In some cases, your teacher may provide a list of questions that should be answered in this section. If this is the case, remember to reference this list and make sure all questions have been addressed in your text. These questions can also potentially serve as a useful way to organize your analysis and discussion.
Conclusion
Sometimes, a concluding sentence or two is written at the end of the previous section (Analysis and Discussion), and sometimes it is given its own section. Either way, you will summarize your big takeaways from the experiment (what you were testing and whether your results support your hypothesis or not). This is usually the section of your AP Chemistry lab report that makes you think a lot about the big picture of your experiment.
Works Cited
In this final section of your lab report, you will list all sources you used to create your lab report. At the minimum, this should include your provided lab manual and textbook. If you used any other books or online sources, make sure to list them here as well. Your teacher will likely provide you with the preferred lab report format for this section, but if not, ACS format is what you should use.
This section is a good reminder that you can absolutely use outside reliable sources for inspiration and information, but your lab report should always be in your own words and should never contain any plagiarized material.
Now you have learned key tips on how to write an AP Chemistry lab report in the best manner possible. As you go through your AP Chemistry class, you will have plenty of opportunities to create AP Chemistry lab report examples in the format your teacher asks for. To maximize your learning experience, try taking AP Chemistry practice tests in the unit you are covering in class. It will help you pair all the scientific reasoning you did in the lab with the content tested for that unit of the AP Chemistry exam!
