1. GENERAL CHEMISTRY Writing an Experimental Section

2. Why write an experimental section?
One goal: teach you how to design the experiment yourself.
By writing a complete experimental section, you show you are able to decide on the course of action appropriate for the experiment.
To practice writing about standard laboratory procedures in CONCISE language and voice used by chemists.
Report what you did in sufficient detail so another person can REPRODUCE your work.
Use your fellow students as the “audience” of your paper.
The effect of paramagnetism is much stronger than that of diamagnetism.

3. Ten Guidelines to Writing Experimental Sections
Use subheadings
Give specific details
Write in past tense and passive voice.
Use formal language
Avoid ambiguity with formulas, phrases, and formulations.
Avoid ambiguity with numbers.
Pay attention to the chemists’ style.
Avoid relying heavily on the verb to use.
Include information about computation (if necessary).
Remember to note the make and model of the instrument.
The effect of paramagnetism is much stronger than that of diamagnetism.

4. 1. Use subheadings 2. Give specific details
Every experiment will have one or multiple parts; subheadings make the experiment seem understandable from the reader’s point of view as to how you accomplished your goal.
Examples of subheadings (which should be italicized or bolded)
Preparation of EDTA standard solution
Statistical Evaluation of Results
Do NOT write Part I, II, II as a subheading!
2. Give specific details
The effect of paramagnetism is much stronger than that of diamagnetism.
Provide details of operations that are variable (i.e., time, volume, concentration, etc.)

5. 3. Write in the past tense and passive voice
For example you would write:
The reaction mixture was heated under reflux for 20 min, cooled, and transferred to a 100 mL separatory funnel. Hexane (25 mL) was added and the flask shaken for 30 s. After separation, the UV-vis absoprtion spectrum ( nm) of the hexane layer was measured.
DO NOT Write:
You reflux the mixture as per the lab manual, and then we extracted some of the stuff we made into hexane and ran the UV-vis.
The effect of paramagnetism is much stronger than that of diamagnetism.

6. 4. Use Formal Language Words like “stuff” is not appropriate
Do not use the name of a technique as shorthand for making a measurement with an instrument.
Example:
The product was examined by IR spectroscopy.
DO NOT Write:
We ran an IR and saw a vibrational stretch.
You may however use abbreviations of instrumental technqiues (e.g., UV-vis)
The effect of paramagnetism is much stronger than that of diamagnetism.

7. 5. Avoid ambiguity with formulas, phrases, and formulations.
Case scenario:
CH3OH (50 mmol) was added.  No doubt the compound is methanol.
However:
NaOH (50 mmol) was added  Not clear since NaOH can exist either as a solid or in an aqueous solution.
Correct form: Sodium hydroxide (aq) [20.0 mL, 10.0% (m/v)] was added.
The effect of paramagnetism is much stronger than that of diamagnetism.

8. 6. Avoid ambiguity with numbers.
Significant figures!
Example:
Correct form: The mixture was refluxed for 22.5 min.
*There is no doubt the time is to the nearest 0.1 min.
Wrong form: The mixture was refluxed for 100 min.
**Means either time between 95 and 105 min or 99.5 min and min.
The effect of paramagnetism is much stronger than that of diamagnetism.

9. 7. Pay attention to the Chemists’ style.
Example:
Correct Form: Hexane (25 mL) was added….
Incorrect Form: 25 mL of hexane was added….
Note the change from the plural to singular form of the verb.
Note that there is always a space between a number and its unit!
The effect of paramagnetism is much stronger than that of diamagnetism.

10. 8. Avoid relying on the verb to use.
Example:
Incorrect form: A top-loading balance was used to obtain approximate weights, then a four-place analytical balance was used to determine the precise weight of the potassium hydrogen phthalate.
Identify the action and substitute the phrase to use with more specific verbs.
Correct Form: Approximate weights of potassium hydrogen phthalate were obtained with a top-loading balance followed by precise weighing, to four decimal places, on an analytical balance. Solutions were transferred with bulb pipets and titrations performed.
The effect of paramagnetism is much stronger than that of diamagnetism.

11. 9. Include information about Computation.
Describe the mathematical treatment of quantitative data
Provide information about any computer software used.
10. Note Make and Model of Instruments.
The effect of paramagnetism is much stronger than that of diamagnetism.
Always check any instruments you use in lab and record what they are for reproducibility purposes.