Writing a Formal Lab Report Mrs. Storer Chemistry

Why should students learn to write lab reports? It is a skill needed if you embark on a career in science. In writing a report you are forced to reflect on what they had done, and provides practice in critical thinking. Other reasons?

Ability to write lab reports is a necessary skill in science. It is a skill needed no matter whether you end up in a graduate school, research institution or industry You need to learn to report results obtained in an experiment. Results to be published must be in the format required by the publisher.

What have we required in the past in chemistry classes? 70 ’ s and 80 ’ s, and currently in some large universities: Fill out a sheet of data, do some calculations and report a final result. e.g. Unknown A contains 48.2% KCl. The last years, the trend has been to push students to do more critical thinking and learn to express themselves better.

Lab Report Format 1. Cover page 2. Purpose 3. Hypothesis 4. Materials list 5. Safety 6. Procedure 7. Data and/or observation table(s) 8. Calculations (if any) and Results 9. Discussion and Conclusions

1. Cover page Your 2-3 page typed report needs to include: Title Date of Report Name of author of report Lab Partner(s) Graphic/ picture that is related to the concept at hand

2. Purpose The purpose should be a statement of the question being investigated. For example, “How does the density of the elements change as you travel down the oxygen family?” is incorrect. Rather, something along the lines of “Density trends in the oxygen family will be investigated” would be appropriate.

3. Hypothesis: The hypothesis should be a prediction that answers the question of the purpose. The expected results, based upon your background knowledge, should be stated. The hypothesis may be incorrect, but the original hypothesis should be stated, regardless of whether or not the hypothesis is proven wrong in the course of the lab.

4. Materials List Just what is sounds like, provide a complete list of the materials you used in the lab.

5. Safety Information about safety precautions taken (goggles, hair up, etc) as well as Information about the safety of the materials should also be listed.

6. Procedure A detailed, but concise, description of the investigation that would allow others with a similar background to replicate the experiment exactly should be provided. Information that would not affect the outcome of the investigation does not need to be provided. Diagrams may help clarify a complicated or unique set up, and are a welcome addition to any report.

Always write the procedure in Passive Voice Passive voice is used when describing a procedure in a report because generally who is doing the work, or who is making the observations is not important. Presumably, anyone with lab skills should be able to get the same results.

Let ’ s try passive voice! Rewrite the following sentences in passive voice. 1. I transferred the contents of the beaker to the graduated cylinder. 2. I found the slope of my graph to be 0.04 g/min. 3. I added 3 drops of bromophenol indicator to the Erlenmeyer flask.

When is passive voice not necessary? As a rule of thumb, it is not necessary for passages other than the procedure. The active voice is preferred to keep the passage less wordy, more direct and less awkward. HOWEVER…generally we do not use the first person singular pronoun.

7. Data and observations tables: Data refers to the numbers, while observations are the qualitative pieces of information collected. All data and observations collected should pertain to the stated purpose of the investigation. Data should not include calculations, or be interpreted. Observations should be listed, and not interpreted or related to cause. Organize in tables or charts.

8. Calculations and Results Results should include anything done with the data, such as a calculation, or the integration of data into a graph. Formulas for each calculation are expected, Analyze results and state if they are comparable to the acceptable, published values. Percent error, a comparison of the expected (also called actual value) to the experimentally established value, is one way to do this and should be included when possible.

9. Conclusions and Post-lab Questions State the meaning of the data and results. The goals, general methods, and conclusions should be included. Evaluate how well the experiment addressed the question, and if the hypothesis was correct. If the hypothesis was incorrect, this is the place to deal with why, as well as any implications that arise. Relate how the lab connects to what we have been studying. Answer any post-lab questions

One last thing: Do not use “ I ” in your report! For examples : use "we" or "one" instead of "I": From the color of the endpoint we can conclude that the equivalent point has been reached. From the color of the endpoint one can conclude that the equivalent point has been reached

And last but not least! After you are finished, review the report. Use spell check. Be sure that all figures (charts, tables, graphs, diagrams and pictures) are labeled with appropriate axes, titles, and legends. All sections should be written in passive, rather than active, voice. For example, use statements such as “ the solution was heated for one hour at 50˚C ” rather than the active “ I heated the solution for one hour at 50˚C ”. No personal pronouns should be used. Be sure that all goals of the study, as stated in the introduction, are addressed.