From: glhurst@onr.com (Gerald L. Hurst)
Newsgroups: alt.engr.explosives,sci.chem
Subject: Re: Explosives and powders questions
Date: 25 Nov 1995 20:07:36 GMT
Organization: Consulting Chemist
Lines: 65

In article <496ihk$rk5@hades.omen.com.au>, you@somehost.somedomain
(Trevor Finnie) says:

>In article <480lj8$ies@geraldo.cc.utexas.edu>, glhurst@onr.com says...
>>
>>In article <47v23g$nne@soap.news.pipex.net>, rdicken@solo.pipex.com (Robert 
>Dicken) says:
>>
>>>Could someone let me know what "powdered chlorine" is please, I
>>>understood that chlorine is a gas at room temps and a nasty one at
>>>that.
>>
>>The term is often used to describe calcium chlorohypochlorite, CaClOCl.
>>
>>Jerry
>
> 
>As far as I know it is in fact Calcium Hypochlorite, CaClO. It is usually in
>a 65% concentration in pool chlorine.
>
>Trev.

Trev, you need to do a little work on that e-mail return address. My 
reply to you bounced like an AOLer's check.

The formula for calcium hypochlorite is Ca(OCl)2. As far as I know
this compound has never been actually isolated. When Moses and I
were in school, they taught us about "bleaching lime" which is made 
by chlorinating lime to create some hypochlorite ion.  Remember that
sodium hypochlorite solution, ordinary liquid bleach, is made by
the reaction 

2NaOH + Cl2 --> NaCl + NaOCl + H2O

This particular hypochlorite is unstable when dry, so we normally 
only see it as a solution with at least an equal amount of sodium 
chloride. For all practical purposes we could that we have a 
solution of the hypothetical double salt "sodium 
chlorohypochlorite," Na2ClOCl. That is, we could, but we don't:)

If we write the analogous equation for lime it looks like this:

Ca(OH)2 + Cl2 --> 1/2CaCl2 + 1/2Ca(OCl)2 + H2O

or

Ca(OH)2 + Cl2 --> CaClOCl + H2O

They may or may not have done enough work in characterizing the 
product to tell if it is a double salt or a mixture, but some
refer to it as "calcium hypochlorite" and others a "calcium 
chlorohypochlorite" to keep in mind the presence of the chloride
ion. Some of the older scrolls say the material is ternary mess
which also contains lime. 

There is still a little puzzle here regarding that 65 percent
figure. My notes (which are often wrong or at least unlegible)
say that the label on the commercial material claims "65% 
chlorine." That figure does not seem to compute because 
neither of the above compounds contains that much chlorine
in its anions.  Maybe the lable said something else. You don't
suppose they would fib, do you?

Why don't we publish this note in sci.chem? What are friends for?

Jerry