How to solve CoCl2+HO2- ------> Co(OH)3+ Cl- by half reaction method

3 answers

Co^2+ ==> Co^3+ + e
HO2^- + 2e + H2O ==> 3OH^-
Multiply eqn 1 by 2 and add. Cancel the 2e on each side.
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2Co^2+ +HO2^- +H2O=> 3OH^- +2Co^3+

You can add in the Cl^- here as
2CoCl2 + HO2^- + H2O ->2Co^3+ + 3OH^- + 4Cl^-
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You can make that 2Co^3+ on the right as 2Co(OH)3 BUT you have only 3 OH^- there to do that so you must add 3OH^- on the left side, too, as
2CoCl2 + HO2^- + H2O + 3OH^- ==> 2Co(OH)3 + 4Cl^-

1. Atoms balance on each side.
2. change e balance
3. charge balances on each side.
Ty
Happy baddeyyy!