Greg,

The other down side to the peroxide approach, aside from the consumption
volume difference and stability of the peroxide itself, is that if you
overdose the system with peroxide, large amounts of chlorine gas will be
evolved...a dangerous proposition.

The balanced reaction is:
H2O2 + 2HCL + Cu --> CuCl2 + 2H2O

Excess peroxide will react with free HCl acid to create water and free
chlorine gas: (1:2 mole ratio)
(H2O2 + 2HCl --> 2H2O +Cl2)

So an excess peroxide reaction is:
2H2O2 + 4HCl + Cu --> CuCl2 + 4H2O + Cl2

Sorry about the font layout...I can't do subscripts in Eudora.


At 02:05 PM 12/5/01 -0600, you wrote:
>Hey Greg, long time no talk to. The most common oversight in comparing
>peroxide and chlorate is understanding consumption and by-products
>generated from the reaction. The reaction using peroxide generates 1 mole
>of water for 1 mole of cupric chloride regenerated, the reaction using
>sodium chlorate generates 1 mole of water for 2 moles of cupric chloride,
>half as much water. Also, 1 mole of peroxide consumes 1 mole of copper
>whereas 1 mole of sodium chlorate consumes 3 moles of copper. The volume
>consumption of 50%by weight Hydrogen Peroxide is 3 times that of CuOx, e.g.
>if a process consumes 100 gallons of peroxide per day, when switching to
>chlorate they will only use app. 33 gallons of chlorate in the same
>conditions. Given the other dilution and stabilization issues with peroxide
>it is common for the consumption difference to be closer to 4 times that of
>sodium chlorate.
>
>Salt is a by-product generated in the chlorate reaction, which my of us add
>over the side to increase etch rate.
>
>Alot of water is generated in the peroxide reaction, which somtimes makes
>it difficult to maintain Cu loading. Hope this helps,
>
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