Question

When potassium dichromate crystals are heated, we get

• A. oxygen
• B. hydrogen
• C. sulphur dioxide
• D. hydrogen sulphide

Answer 1

Answer: (A)

oxygen

Answer 2

Potassium dichromate, on heating, gives oxygen and green chromic oxide $\left( Cr _{2} O _{3}\right)$ vapour. $4 K _{2} Cr _{2} O _{7} {->[\Delta]} 4 K _{2} CrO _{4}+\underset{\text { green }}{2 Cr _{2} O _{3} \uparrow}+3 O _{2} \uparrow$ Though ammonium dichromate, on heating gives nitrogen gas. $\left( NH _{4}\right)_{2} Cr _{2} O _{7} {->[\Delta]} N _{2}+ Cr _{2} O _{3}+4 H _{2} O$