# Lab Reporting: How to Write an Informal Lab Report

How to Write an Informal Lab Report:

Labs turned in with formatting other than an informal report such as filling in the blanks and data tables from the printed lab, etc. will start grading at half credit.

In this course, two labs will require a formal lab write up and eight labs will require an informal lab report write up. The informal report will focus on the results and analysis from your lab. Although it is abbreviated, it contains tabulated data as well as writing including complete sentences and short paragraphs where required. First person writing is acceptable in an informal lab report. In general, your informal report should be organized with the following clearly labeled sections organized in this order.

Tabulated Raw Data:

Your data validates your findings and can help problem solve errors in your results. Include your raw data such as mass, volume, temperature, concentration, etc. Sample data tables are often included in your lab, but you must create organized and labeled data tables that match your procedure. A linear regression displays corresponding data points as a line and must be displayed with axis labels and an equation of the line. Include the number or letter of an unknown with your raw data.

Formulas and Equations:

Include any chemical equation used in your lab work. If an equation is included as background or an example, but not used for calculation, you may omit it. You must include mathematical equations used such as density, wavelength and diffraction, percent composition, calorimetry, ideal gas, etc. Stoichiometric functions and Hess’ law formula additions are not equations, and your sample calculations suffice in this regard.

Sample Calculations:

You must include sample calculations. If you repeat a calculation more than once, for multiple trials, etc. you may include one sample calculation. Stoichiometric analysis should be included. You should include a sample calculation for statistical analysis such as percent difference, relative standard deviation, and percent error as well.

Findings:

Include your findings with correct significant figures and units. Why did you perform the lab and what results did you produce? Examples of your results include density, percent composition, a chemical formula or ratio, width, concentration or identity of an unknown, energy per mole, or the mass and volume needed to create a product. Include the letter or number of an unknown once again in this section. Include statistical analysis. Examples of statistical analysis include percent error, percent difference or relative standard deviation. You must have at least two quantitative data points to perform statistical analysis. Not every lab will, therefore, include statistics. Discussion of your findings is appropriate in this section. Were there errors that account for a deviation from expected results? What caused the errors, and in which direction did the data skew?

Post Lab:

Include numbered responses to lab questions. Do not re-write the question. Use complete sentences or short paragraphs as appropriate. You do not need to include the pre-lab questions in your post lab report. They will be addressed in the pre-lab quiz.

In addition to these guidelines, each lab contains instructions specific to the lab’s measurements and analysis.