Question

Which of the following is a product of first step and is used as reactant in next step for manufacture of K₂Cr₂O₇ from concentrated chromite ore?

Options

• Sodium dichromate

• Sodium sulphate

• Sodium chromate

• Potassium chromate

Answer 1

Sodium chromate

Explanation:

1. Conversion of chromite ore into sodium chromate

\[\ce{\underset{\text{Chromite ore}}{4FeCr2O4} + 8Na2CO3 + 7O2 -> 2Fe2O3 + \underset{\text{Sodium chromate}}{8CO2 + 8Na2CrO4}}\]

2. Conversion of sodium chromate into sodium dichromate

\[\ce{\underset{\text{Sodium chromate}}{2Na2CrO4} + H2SO4 -> \underset{\text{Sodium dichromate}}{Na2Cr2O7} + Na2SO4 + H2O}\]

3. Conversion of sodium dicbromate to potassium dichromate

\[\ce{\underset{\text{Sod. dichromate}}{Na2Cr2O7} + 2KCl -> \underset{\text{Pot. dicbromate}}{K2Cr2O7} + 2NaCl}\]