How to Write a CHEM111B Laboratory Report
In this course, all of your experiments will be written up as proper reports. A laboratory report consists of the following separate sections:
1. Title
2. Introduction
3. Experimental
4. Results and Discussion
5. Conclusion
6. References
1. The Title of your report should be at the top of the first page, and be a one-line summary of what the experiment was about. For most of these experiments, you can simply copy the title from the procedure we give you.
Example: Experiment 7: Computer Graphing
2. The Introduction section should be a very short description (say 2-3 sentences) of what you were trying to do in the experiment. It is meant to give the reader an idea of what you were trying to show, and how you were doing it.
Example: The Excel program was used to generate different graph types from given data in this experiment. Various exercises demonstrating graph formatting and scaling, and the application of the Excel Trendline feature, were performed and are summarized.
3. The Experimental section should provide the reader with enough information that they can understand what you did, and if it were necessary, repeat your experiment. It should summarize what you OBSERVED when following the procedures. This section needs to be concisely written, but make sure that all the important information is included.
Example: After mixing solution A with solution B the resulting solution turned red. This experiment was performed according to the procedures as provided in the CHEM111B laboratory manual: Po, Henry and Senozan, N. “General Chemistry Experiments CHEM111B”, pp 33-40
This is an experimental result but doesn’t contain anything about how much, what concentration, etc. Those specifics can be referenced as done above. For most of your reports, you will be following the procedures that are given to you. You have to fully detail the source, including authors/title/edition/publisher/ year/page numbers!
If you changed any of the listed procedures, then you have to mention these. For example, if you added 12 drops of NH3 instead of the 8 in the procedure you would say:
Example: However, for the determination of copper in this unknown sample, 12 drops of ammonia were added to the test-tube rather than eight.
4. The Results and Discussion section is the “meat” of your report, where you summarize the data you determined in your experiment, and discuss what it means. The Results and Discussion section should include an EXPLANATION of what was OBSERVED in the experimental section. Observations that are important need to be included, for example, if your solution turned blue when you added ammonia to your aqueous solution – which implies that there was copper in your unknown sample – you need to state this. You need to include important changes like precipitates forming, temperature changes, color changes in solutions, etc. and also what these findings imply! At all times when discussing your observations you need to include balanced chemical equations.
Example: The red color appearing in the solution that resulted from the mixing of solution A and solution B is due to a shift in the equilibrium towards products. This is related to Le Châtelier’s principle whereby the reaction restores equilibrium after additional solution A, a reactant, is added to the solution.
Results should be summarized into Tables and Graphs wherever possible, with appropriate captions describing what they represent. Remember that captions should be put above Tables and below Figures. All Tables and Figures must be numbered in sequential order.
If you have a number of data points that need to be manipulated, give one “typical” example of your calculations, and summarize the other final values in a Table.
If your experiment value has previously been measured, you should compare these data to your value. You have to properly reference any literature that you include in your report, these references should be in numerical order at the end of your report (after Conclusions). If your determined value is different to the literature, you need to discuss why this might be so. You should especially discuss potential errors that might have influenced your measurements, and give an idea of how accurate your experimental value is. Remember to use correct significant figures when reporting data and final values!
Each Results and Discussion section will be different, but remember – you are trying to explain what you found, and what it means, to another scientist. You need to be concise, but include all important information.
5. Conclusion. A very brief summary of what you found in this laboratory exercise.
Example: From the decomposition of calcium carbonate in a closed system at 800K the Gas Constant R was found to be 8.314 J K-1 mol-1.
6. References: Be consistent with your style of literature citations – as chemists we use the American Chemical Society style (see below). Within the body of the paper give name(s) and year published for one or two of the author citations. If more than two authors wrote the paper, give the name of the first author followed by et al. and the year published. In the References section, be sure to list all the authors! For example
In body of text: Colbert et al. (1990) found that the gas constant……
In References: Colbert, S.R.; Jokela, E.J.; Neary, D.G. J. Phys. Chem. 1988, 92, 842.
The names are given as Surname, Initials followed by semi-colon, the Journal is given in Italics, the year in Bold, the Journal number (if relevant) in italics, and the page number at the end.
Reports are always written using the 3rd person (for example, you would say “3 drops of ammonia were added” NOT “I added 3 drops of ammonia”) and in the past tense.
Always spell- and grammar-check your report before you hand it in!
Formatting: To be consistent your laboratory reports should be written using a word-processing program. Please use double-spacing and 1” margins throughout. Graphs should also be generated by computer (Excel), and copied into the Word document. Chemical formula should be properly written with subscripts (e.g. CH3OH), temperatures should have degree signs (Use Insert Symbol, ° is just after the regular letters in the Normal Font; e.g. 25°C).
All pages should be sequentially numbered, with the numbers centered at the top of each page. Your name and ID number should also be on every page.
