Question

Anhydrous potassium nitrate is heated with excess of metallic potassium $KN{O}_3\left(s\right)+K\left(s\right)\to X+Y$ In this reaction , the products X and Y are

• A. $KN{O}_2,O_2$
• B. $K_{2}O,N_2$
• C. $K_{2}O,N_{2}O$
• D. $K_{2}O,N{O}_2$

Answer 1

The correct option is B

$K_{2}O,N_2$

Between 550–790 °C, potassium nitrate reaches a temperature dependent equilibrium with potassium nitrite:

$2KN{O}_3\rightleftharpoons 2KN{O}_2+O_2$

But this is not the question. If we look carefully, solid anhydrous potassium nitrate is strongly heated with excess metallic potassium. The alkali metal is definitely a reducing agent:

$2KN{O}_3\left(s\right)+10K\left(s\right)⟶6K_{2}O\left(s\right)+N_2\left(g\right)\uparrow$