Jome - 5-12-2005 at 02:18
Reaction w. an acid and hypochlorite yields chlorine, but how does the reaction go?
Something like this?:
H2SO4+NaClO(aq)--->NaHSO4(aq)+HClO(aq), 4HClO is dehydrated by H2SO4 into 2 mol of Cl2 and 1 mol of O2.
w. HCl(aq) one would get something like:
HCl(aq...)+NaClO--->NaCl+HClO HClO+HCl-->H2O+Cl2?
Is this correct?
neutrino - 5-12-2005 at 03:24
Your second equation is correct. The net ionic equation here is:
Cl- + ClO- + 2H+ ---> H<sub>2</sub>O + Cl<sub>2</sub>
Note that a source of chloride ions is unnecessary when using bleach or pool chlorinator, because these already have a stoichiometric amount.
woelen - 5-12-2005 at 11:43
The last remark is not always true. I have calcium hypochlorite, Ca(ClO)2.2H2O. This compound has no chloride (well, it has, but only as impurity).
If you add some dilute HNO3 to this, then you do get some Cl2, but the reaction is much slower than when dilute HCl is added.
Ca(OH)2 addition
chloric1 - 5-12-2005 at 12:54
From the processes I have read about, the Ca(OH)2 is chlorinated to the hypochlorite and addtional Ca(OH)2 is added to precipitate with the chloride
the insoluble double salt CaCL2*Ca(OH)2. This also help to stabilize the hypochlorite. This is important because even a small amount of oxidizable
contaminent introduced into a large mass of the hypochlorite could cause an autocatalytic decomposition of the ENTIRE mass of product possibly
rupturing the container or much worse. I believe once a small portion reached 180C from external heating or by chemical reaction the autocatalytic
throughout the mass commences. 
neutrino - 5-12-2005 at 14:22
I didn't know about that purification step. Now that I do the math, 70% calcium hypochlorite would have a lack of chloride if left untreated. Thanks
for pointing this out.