To balance the equation, Hydrogen ion should be added to the left of the equation and water to the right of the equation as follows:
[tex] H^{+} + Cr^{2+} + H_{2} Mo O_{4} ---\ \textgreater \ Cr^{3+} + Mo + H_{2} O[/tex]
Balancing the equation
[tex]6 H^{+} + 6 Cr^{2+} + H_{2} Mo O_{4} ----\ \textgreater \ 6 Cr^{3+} + Mo + 4 H_{2} O [/tex]
It can be noted that: ions are balanced at 18+ on left hand side and 18+ on right and side just like all the other chemical elements.