How safe is too safe?

I got an email this week from a chemistry teacher at a small private school.  She had been teaching for a couple of years using only reagents that posed no real possible danger for students under any circumstances – think acetic acid instead of hydrochloric acid and so forth.  She was concerned that she was being far too conservative when thinking about safety and limiting her students in what they could learn in the lab.  What would I suggest she do?

This is a good question, and one that I think isn’t asked enough.  When working in a chemistry lab, there’s always a balance that needs to be struck between making the lessons interesting and useful, as well as making the labs safe enough that nobody can ever get hurt.  On one extreme is a lab in which the only reagents are baking soda and vinegar – in this case there’s no danger of injury but also a limit to how much that can be learned.  On the other extreme are labs that examine how aqua regia and hydrofluoric acid react with common substances – interesting and instructive, but suicidally dangerous for the kids.

What I told this teacher is that you simply cannot be too conservative when safety is considered.  If there’s even the slightest doubt in your mind that a lab can be done safely, then don’t do it.  Even if you feel like baking soda and vinegar are too dangerous to use, then you should absolutely not use them in the lab.  It doesn’t matter what the other teachers at your school do and it doesn’t matter what the lab manual says.  Never, ever perform a lab with reagents that you feel uncomfortable using.

This is not to say, however, that you can’t use interesting reagents.  The key here is to educate yourself about how to use them safely.  If you currently just use baking soda and vinegar but are interested in titrating sulfuric acid, there’s no reason why you can’t.  Provided, of course, that you fully understand your own limitations, the limitations of your students, and the limits of your safety equipment.

Before performing any lab, you should always ask yourself the following questions:

  • Do I understand the dangers of using the reagents?  If you understand all of the dangers of using the reagents – reactivity, flammability, storage, and so forth – then you can consider the lab.
  • Are my students able to handle this lab safely?  If you have four classes that are mature and one class that is not, it’s probably a good idea to either let only four of the classes do a particular lab, or alternatively, cancel it for everybody.  Even if a lab should be safe, always consider your students.  And if you haven’t ever taught your kids the basics of working with hazardous chemicals, now is a good time to do it.
  • Do I have the lab equipment to handle everything safely?  If you need to transfer a reagent from one place to another, are you certain that you’re using the right tool for the job?  And do you have the waste container needed to handle whatever is produced?
  • Do I have the safety equipment to deal with a problem?  If you don’t have goggles and some kind of eyewash, you can’t do anything that involves non-eye safe reagents.  If you don’t have a fire blanket, you shouldn’t use flammable reagents – and a safety shower is much better!
  • Have I done the lab before, or has somebody I know done it before?  If you don’t know somebody who’s done a lab before, this doesn’t mean that you shouldn’t do it.  However, it does mean that you need to run through it yourself ahead of time with a critical eye.

When you boil it all down to what’s important, the single most important thing in a science class is to make sure your students are safe.  If you have even the tiniest doubt in your head about whether something is safe, don’t do it.  Keep this in mind when planning your lessons for the coming school year, and you should be fine.

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