Question

Complete and balance the following equation :

${\mathrm{KNO}}_3\to \mathrm{\_\_\_\_\_}+\mathrm{\_\_\_\_\_\_}$

• A. KNO₂(s)
• B. O₂(g)

Answer 1

• When potassium nitrate is heated, it decomposes into Potassium nitrite and Oxygen. This is an example of a decomposition reaction.
• A decomposition reaction can be defined as a chemical reaction in which one reactant breaks down into two or more products.

${\mathrm{KNO}}_3\left(\mathrm{s}\right)\stackrel{∆}{\to }{\mathrm{KNO}}_2\left(\mathrm{s}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)$

Balancing-

• Multiply KNO₃ by 2 to get 6 oxygen atoms on the reactant side.
• Multiply KNO₂ by 2 to balance the Potassium atom on the product side.
• We get 6 Oxygen atoms on both sides.

Hence, the complete balanced equation is-

$\underset{\mathrm{Potassium}\mathrm{nitrate}}{2{\mathrm{KNO}}_3\left(\mathrm{s}\right)}\stackrel{∆}{\to }\underset{\mathrm{Potassium}\mathrm{nitrite}}{2{\mathrm{KNO}}_2\left(\mathrm{s}\right)}+\underset{\mathrm{Oxygen}}{{\mathrm{O}}_2\left(\mathrm{g}\right)}$