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The focus of my question here is this: In a laboratory there is a Bunsen burner, a hot plate, hydrochloric acid, and concentrated ammonia. What would you mention about safety precautions?

As students of chemistry and science, we often need to write detailed conclusions about our laboratory experiments. This eventually becomes second-nature, but to have an an idea of which of the safety measures taken to include are often useful to ensure ourselves that we have not left anything out.

I believe that the following are some of the the most important components of any well written conclusion in a lab entry, something that your lab instructor will read and grade you on.

  • Purpose: Explain the goal and purpose of the experiment in a clear and concise manner.

  • Findings: Presents a reasonable interpretation of, and logical explanation for all findings pertaining to the problem and stated purpose.

  • Discussion: Discusses possible sources of error in detail, including their effect on the results and ways of avoiding them in the future.

  • Referencing experimental findings and explaining the known/expected results we were looking for. Mentioning and discussing reasons for trends, if any.

In particular my instructors last year were often interested in:

  • Safety: This is often what I always got marked down for. I would explain that hydrochloric acid is a caustic substance and should be treated with care to not get on your tissue by wearing clothing that does not expose skin and closed toe shoes, and to always carry out the experiment with safety goggles securely fastened. It never seems to be enough for them, even if I mention eye flush and chemical shower in case of emergencies. Should I mention to not snort or freebase it? /end sarcasm

Have I missed any safety components that should be included in a "complete" conclusion for the average experiment? What else might I have left out that instructors tend to look for?

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Perhaps your instructors want more specific information about the hazard itself, rather than generic safety advice. Some examples:

1) HCl: Strong acid, highly corrosive (nitpick: caustic is usually reserved for strong bases, corrosive for acids), emits corrosive and toxic fumes (not all acids do)

2) 29% NH4OH: Caustic, emits strong fumes (lachrymator--makes your eyes water), work in a fume hood, outdoors or in a well-ventilated area

3) Bunsen burner: No open flames in the presence of flammable vapors or liquids with high vapor pressure (much bigger hazard than just burning yourself)

4) Hotplate: Hotplate looks the same whether hot or cold, so assume it is hot, take care with flammable liquids with low flash points

Again, these are just examples, but I tried to tailor the answer to the item in question.

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  • $\begingroup$ Stumbled across this very old thread, but I'm a firm believer in safety. // As former teaching assistant who worked a lot of freshman labs, one of the real problems was safety goggles/glasses. They are like blinders on a horse. So you must turn and look before going off in a different direction. $\endgroup$ – MaxW Jul 8 at 14:56

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