In our chemistry practical paper (High school level), Inorganic salt analysis is one of the questions asked. We are given a petri dish with a sample of salt and are asked to find the cation and anion present in it.

I noticed quite a few of my classmates touching the salt (pinching it between their fingers and sprinkling it, similar to what you would do with table salt). Is this safe? Note that we do not have much in the way of PPE (No gloves, eyewear, only a lab coat). For reference, the cations may be any one of the following:

  • $\ce{NH4+}$
  • $\ce{Pb^2+}$
  • $\ce{Cu^2+}$
  • $\ce{Al^3+}$
  • $\ce{Zn^2+}$
  • $\ce{Sr^2+, Ba^2+, Ca^2+}$

The anions are $\ce{CO3^2-}$, $\ce{Cl^-}$, $\ce{NO3-}$, $\ce{SO4^2-}$ and $\ce{CH3COO-}$ (I don't believe these pose much of a health hazard)

The first thought is that this is very unsafe as the salt may be a lead/strontium/barium salt and you might end up ingesting a few milligrams if you don't wash your hands. Otherwise, I cannot see any further hazards here.

Is there anything that I have missed in my analysis? Any further thoughts on the safety of this procedure are welcome.

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    $\begingroup$ The students should never ever touch salts with their bare hands. There is no need to. Skin readily absorbs many things. In short it is a very bad practice and the teachers should keep their eyes open in the labs. One can understand that some Indian colleges and high schools are overpopulated with 40-60 students in lab session. Still if you see your class fellows doing this tell them not to do so. $\endgroup$ – M. Farooq Jan 24 '20 at 2:46
  • $\begingroup$ @DrMoishePippik is there supposed to be a link in your comment? $\endgroup$ – Aniruddha Deb Jan 24 '20 at 5:23
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    $\begingroup$ You won't get dramatic consequences in a normal scenario. But there is no need to do so, first of all. You might soon pass from qualitative to quantitative. Or the assistant can put something wrong in the Petri, and so on. $\endgroup$ – Alchimista Jan 24 '20 at 9:03
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    $\begingroup$ Downvoters, please clarify the reason for the downvote. It seems like a valid question to me :/ $\endgroup$ – Aniruddha Deb Jan 25 '20 at 9:37
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    $\begingroup$ Pb, Ba (and Hg) are particularly nasty. Read the cautionary obituary, mentalfloss.com/article/501147/… . N.B. She had on gloves! $\endgroup$ – DrMoishe Pippik Jan 25 '20 at 23:49

The comments more or less say it all. Wearing gloves is a good idea with just about any chemical, not only to protect you but also to protect the chemical from contamination. For instance, if you find chloride in your sample you might want to be sure said chloride is not from salt on your skin.


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