Question

$Na_2CrO_4 \xrightarrow{A} Na_2SO_4 + \underset{\text{Orange}}{B} \rightarrow \underset{\text{Orange Red}}{C} + NaCl$
A, B and C respectively are:

• A. $K_{2}SO_{4}, K_{2}CrO_{4}$ and $K_{2}Cr_{2}O_{7}$
• B. $K_{2}SO_{4}, Na_{2}CrO_{4}$ and $Na_{2}Cr_{2}O_{7}$
• C. $H_{2}SO_{4}, NaCrO_{2}$ and $K_{2}Cr_{2}O_{7}$
• D. $H_{2}SO_{4}, Na_{2}Cr_{2}O_{7}$ and $K_{2}Cr_{2}O_{7}$

Answer 1

Answer: (D)

This reaction is the method of preparation of $K_{2}Cr_{2}O_{7}$
$2Na_{2}CrO_{4} + H_{2}SO_{4} \to \underset{\text{Sodium dichromate (orange)}}{Na_{2}Cr_{2}O_{7} + Na_{2}SO_{4}} + H_{2}SO_{4}$
$2Na_{2}Cr_{2}O_{7} + 2KCl \to \underset{\overset{\text{Potassium dichromate}}{\text{(orange red)}}}{K_{2}Cr_{2}O_{7}}+2NaCl$