J.R. S. answered 04/23/22
Ph.D. University Professor with 10+ years Tutoring Experience
N2H4 + Cu(OH)2 ==> N2 + Cu ... unbalanced
N2H4 ==> N2 ... oxidation half reaction
N2H4 +4OH- ==> N2 + 4H2O ... balanced for N, O and H using base (OH-) and H2O
N2H4 +4OH- ==> N2 + 4H2O + 4e- ... balanced for mass and charge
Cu(OH)2 ==> Cu ... reduction half reaction
Cu(OH)2 ==> Cu + 2H2O ... balanced for Cu and O
Cu(OH)2 + 2H2O ==> Cu + 2H2O + 2OH- ... balanced for Cu, O and H using base (OH)- and H2O
Cu(OH)2 + 2H2O + 2e- ==> Cu + 2H2O + 2OH- ... balanced for mass and charge
Since the reduction half reaction has only 2e-, we must multiply it by 2 to equal the electrons in the oxidation half reaction. This gives us a reduction half reaction of 2Cu(OH)2 + 4H2O + 4e- ==> 2Cu + 4H2O + 4OH-
Add this to the oxidation half reaction and we have...
N2H4 +4OH- + 2Cu(OH)2 + 4H2O + 4e- ==> N2 + 4H2O + 4e- + 2Cu + 4H2O + 4OH-
Combining and cancelling like terms, we end up with our final balanced redox equation:
N2H4 + 2Cu(OH)2 + ==> N2 + 2Cu + 4H2O ... BALANCED REDOX EQUATION