A chemistry lab report must meet a range of criteria, which depends not only on the level of study/research you are at, but also on the topic you are writing about, and the audience it is targeting.
All chemistry reports will start life in a laboratory notebook. This is where you keep a record of all your observations, measurements and anything else that needs to be accounted for as the experiment goes on. This has a whole set of rules of its own – it has to be accurate, legible and consistent, so no ripping pages out or forgetting to date your work. However, sharing the results of an experiment doesn’t stop with your lab book. Most findings will eventually need to be presented to others (often the ones brandishing the money or the markbook) in the format of a slideshow, poster or most likely, a lab report.
The difference between a lab book and a lab report is simple. A lab book does not provide context or discussion, a lab report does.
A good lab report should always start with an abstract and an introduction. The abstract is a quick summary of the experiment and its findings – so if you were sorting through a pile of them, you’d know which ones were relevant to your research. The introduction is where the context comes in. There are very few experiments these days that are not building on the work of others, and this is your chance to discuss their findings, and explain why your research is going in the direction you have chosen. You can discuss the theory behind the experiment, the aim of the work and the usefulness of the product you are going to produce (particularly for organic synthesis reactions). Try and keep it concise but exciting – you want to keep people reading, not send them to sleep.
Next comes the results of your experiment. Don’t pack it with too many calculations or graphs – anything that breaks up the text too much should be included at the end in an appendix, so don’t be scared to refer the reader to other pages. Be objective. If the experiment didn’t give you the results you were hoping for, be honest about it. There’s plenty of room to explain what happened in the discussion section. Describe anything that might be helpful to other scientists – what your product looked like, how much you made, whether it smelled like almonds or alcohol.
The discussion is the most important part of a lab report. This is where you can talk about your findings in depth, and if things didn’t go as you hoped, you can discuss the reasons why. Obviously in a commercial situation, lab reports are usually submitted only for completely successful syntheses, but in real life, not every experiment will work every time, and most scientists appreciate this.
The vital thing here is to explain your results. If you forgot to add water or someone smashed the vacuum seal, talk about it. You want to appear in control of the situation and aware of how your experiment went, even if you were disappointed. Also, at this point, don’t forget if possible to refer back to the theories first mentioned in your introduction. If the experiment has to do with hard and soft nucleophiles, mention it. The discussion should be the longest part of your report, so don’t hold back! Back everything up as much as possible. Use your spectroscopic values, your own knowledge and refer to the work of others.
After the discussion comes the conclusion. This, like your abstract, should be a summary of your findings. However, you should also talk about where you can go from here, or how you could improve on the experiment you carried out. You too will become part of the chain – your research is not the end of the road, so help out the people who are coming after you! If you think adding a particular chemical or waiting a certain amount of time might have helped, make a note of it.
The last written section is always the experimental. The experimental is the nitty-gritty of exactly how you carried out your experiment. The key to this section is accuracy. Everything reagent or solvent mentioned needs to have a quantity, and it should be broken down into manageable steps so that someone else could exactly reproduce what you did. Keep referring to your lab book when writing this section. Don’t waste time describing standard procedures in detail, but do explain if you came up with your own method or modification – no one can read minds; they won’t know unless you tell them. The experimental should also include your spectroscopic data. The exact format of this varies depending on who you are writing for, but most schools/universities/companies have a standard template, so just copy the way they lay things out. The data should have been discussed in previous sections, so the numbers are mostly for posterity.
Follow your experimental with your references. This should be a comprehensive list, the more references the better – this proves you have done your research beforehand. Again, the format varies from report to report, so check how you are expected to lay this out.
Finally, include your appendices. These should be clearly numbered so that the reader can easily find them when reading your report. Most appendices include spectra, graphs, tables, diagrams and/or very long calculations. As long as it’s obvious what it is and why it’s there, there aren’t really any limits to what can be included here. Just don’t fill it with useless information – it’ll make your report look longer, but it will be a pain to sort through.
A quick note on formatting. As I’ve mentioned, most places have a house style when it comes to presenting a report, down to word counts and how to number your references. However, if you can’t find this, the main rule is to keep it straightforward. A simple twelve point font, double-spaced paragraphs and bold titles for each section will usually do the trick. Also, go back to basics – read it through, or get someone else to read it, looking for mistakes in grammar and spelling. Above all, it needs to be easy to read, and have spaces for people to make notes. If you are submitting your report to a publishing company, their website will usually provide a template for you to work from (particularly Elsevier and RSC). Sign and date your work, make sure to include an email address or a phone number for readers to contact you with and wait for the praise to come rolling in.