Cr^2+ + H2MoO4 + H+ → Cr^3+ + Mo + H2O
Cr goes from +2 to +3 or loses one e-
Mo is +6 in H2MoO4 so it goes to 0 gaining 6 e-
so we must multiply Cr by 6 to balance e-
6Cr^2+ + H2MoO4 + H+ → 6Cr^3+ + Mo + H2O
now we balance the spectators
take O first - 4 on left then, change the right side
6Cr^2+ + H2MoO4 + H+ → 6Cr^3+ + Mo + 4H2O
now we have 8 H's on the right
we don't want to touch the H2MoO4
so we make H+ up to 6 for a total of 8 on the left
6Cr^2+ + H2MoO4 + 6H+ → 6Cr^3+ + Mo + 4H2O
Then, It's balanced
