How is pyrophosphate anion, #P_2O_7^(4-)# reduced to elemental phosphorus, with oxidation of hydrogen sulfide to sulphur?
The overal redox equation is:
I take it you mean
Charge and mass are balanced here. Why is that important?
Sulfide anion is oxidized to elemental sulfur:
Charge and mass are balanced again!
So we cross multiply, and
We could make this a little simpler by dividing thru by
Here again, charge and mass are balanced, as required.