Question

Which of the following compounds is used as the starting material for the preparation of potassium dichromate?

• A. K2SO4.Cr2(SO4)3.24H2O (chrome alum)
• B. PbCrO4 (chrome yellow)
• C. FeCr2O4 (chromite)
• D. PbCrO4.PbO (chrome red)

Answer 1

Answer: (C)

FeCr2O4 (chromite)

Answer 2

4FeO. Cr2O3 (chromite ore) + 8Na2CO3 + 7O2 $\overset{\quad Roastinginair\quad}{\rightarrow}$ 8Na2CrO4 + 2Fe2O3 + 8CO2

2Na2CrO4 + H2SO4 $\longrightarrow$Na2Cr2O7 + Na2SO4 + H2O ; Na2Cr2O7 + 2KCI $\longrightarrow$ K2Cr2O7 + 2 NaCl