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Water into Acid or Acid into Water

"steven.h.bergstein" <steven.h.bergstein@ac.com>
12 Aug 96 9:50:34
Gerald Schmalzried wrote:
In chemistry lab, we were taught this rule: Do not pour water into

The reason for the rule is that introducing the first drop of water
(or similarly benign fluid) into acid can potentially unleash all the
chemical energy the acid has to offer, resulting in splattering or
worse unpleasantries. Pouring the acid into the water, however, means
that the first drop of acid is diluted in a virtual swimming pool of
water, and while the rest of the acid is poured in, the mixture
slowly rises to the desired acidic concentration. The process is con-
trolled and not as prone to splattering
Now, it's probably a bit off-topic to discuss this subject, but I hope that 
you'll all forgive me.

I was taught the same thing, but I believe that the reason is different.  If 
you pour water into acid and there is splattering, what will splatter will be 
the acid being pushed out of the container by the momentum of the falling 
water.  Since no one would want relatively undiluted acid splattering on me, my 
clothes or in my eyes, we're told to pour the acid into the water which will 
result in any splattering being the water which was pushed out by the momentum 
of the falling acid.