$$\ce{C2H6O(l) + Cr2O7^{2-}(aq) -> C2H4O2(aq) + Cr^3+(aq)}$$
Basically, I have written the half equations, but I have having trouble with converting ethanol to acetic acid ($\ce{C2H6O -> C2H4O2}$).
I do not know how to balance this. I tried adding $\ce{H2O}$ to either side but I didn't get an equal number of oxygens or hydrogens on either side.