From: glhurst@onr.com (Gerald L. Hurst)
Newsgroups: rec.pyrotechnics
Subject: Re: mixing acids (was Re: How do I make a Pipe Bomb)
Date: 9 Nov 1996 08:31:08 GMT

In article <3280E654.76AC@ix.netcom.com>, The Silent Observer <silent1@ix.netcom.com> says:
>

>> In any case, when mixing acids with water, you add the acid to the water.
>> If you add water to concentrated acid, you run the risk of flash boiling
>> the water due to the heat of solution and splashing steam and acid all over
>> yourself.  Presumably, the same idea would apply to mixing a dilute acid
>> with a strong acid: add the stronger acid to the weaker acid.  I'm certain
>> someone will junp in here and correct me if I'm wrong.  I don't believe
>> that the relative density matters, as another poster suggested.  Again,
>> feel free to correct me if I'm wrong.
>
>One could probably more correctly generalize by advising using the liquid 
>with the lower boiling point as the receptacle, and adding the higher 
>boiling liquid to it.  With some acids, such as HCl, you run the risk of 
>boiling off even a pretty concentrated acid when adding it to a less 
>concentrated acid (for instance, if you are mixing, for whatever reason, 
>partially concentrated HCl and partially concentrated H2SO4, you should 
>probably treat the HCl like the water in the standard example).
>
>Jerry?  Tom?  Can you confirm or refute this theory-based statement?

My approach was always to add the more dangerous material to the less
dangerous one.  That way if the mixture erupts at any stage prior to
complete mixing, the stuff splashing on you is less dangerous.  In the
extreme case, a few drops of additive might blow the entire beaker 
contents in your lap.  At that point your significant other will be glad 
it was mostly water.

Jerry (Ico)