Question

Here's a redox reaction that I've been struggling with...

Cr2O3(s) + Na2CO3(aq) + O2 → Na2CrO4(aq) + CO2


How do I write the half reactions?

Answer 1

check oxidation State and according Just write half reaction
like
Cr2O3 in this let oxidation State of Cr be x
so 2x + 3(-2) = 0
x = +3
now in Na2CrO4
2(+1) + x + 4(-2) =0
x = +6
so here oxidation occur
hence half reaction will be
Cr2O3 -> Na2CrO4
and second Reduction is
O2 -> CO2