Question

Potassium dichromate when heated with concentrated sulphuric acid and a soluble chloride, gives brown-red vapours of ______.

Options

• CrO₃

• CrCl₃

• CrO₂Cl₂

• Cr₂O₃

Answer 1

Potassium dichromate when heated with concentrated sulphuric acid and a soluble chloride, gives brown-red vapours of CrO₂Cl₂.

Explanation:

Solid potassium dichromate when heated with concentrated sulphuric acid and a soluble chloride gives orange red vapours of a volatile oily liquid CrO₂Cl₂.

\[\ce{K2Cr2O7 + 4NaCl + 6H2SO4 -> 2KHSO4 + 4NaHSO4 \underset{chromyl chloride}{+ 2 CrO2Cl2}}\]