In a chrome plating plant, `CrO_4^(2-)` (chromate) ions are present in waste water. The chromate ions are reduced to insoluble chromium hydroxide, `Cr(OH)_3`, by dithionate ion, `S_2O_4^(2-)` in basic medium.
`CrO_4^(2-)+S_2O_4^(2-)+overset(ɵ)(O)H+H_2OtoCr_2(OH_3)+SO_3^(2-)` 10 L of water requires 522 g of `Na_2S+2O_4`. Calculate the normality and molarity of `CrO_4^(2-)` in waste water. .

Explanation

To solve the problem, we need to calculate the normality and molarity of `CrO_4^(2-)` in wastewater based on the given information. Here’s a step-by-step solution:

### Step 1: Understand the Reaction
The reaction involves the reduction of chromate ions (`CrO_4^(2-)`) to chromium hydroxide (`Cr(OH)_3`) by dithionate ions (`S_2O_4^(2-)`). The balanced reaction is:

\[ CrO_4^{2-} + S_2O_4^{2-} + OH^- + H_2O \rightarrow Cr_2(OH)_3 + SO_3^{2-} \]
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