This should be what you need to have it balanced
The correct term that refers to the description that these should be as similar as possible to the real thing is called models. A model serves as a representation of the actual thing which can be used to explain a phenomenon that cannot be experienced directly. It is just a way to help us better understand what the idea, the object or the event is and should not be taken as the real thing.
Reduction
half reaction
2H_2O
+ CrO_4^2- + 3e -> CrO_2^- + 4OH^-
Oxidation
half reaction
2OH^-
+ SO_3^2- -> SO_4^2- + H_2O + 2e
Balanced
overall equation
H_2O
+ 2CrO_4^2- + 3SO_3^2- -> 3SO_3^2- + 2CrO_2^- + 2OH^-
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