Question

On heating a blue colored powder of copper (II) nitrate in a boiling tube, copper oxide (black), oxygen gas, and a brown gas (X) are formed.

Write the balanced chemical equation of the reaction.

Answer 1

1. A balanced chemical equation is one in which the number of atoms is equal on both the reactant and product sides. This means that it follows the law of conservation of mass.
2. When copper (II) nitrate$(\mathrm{Cu}{\left({\mathrm{NO}}_3\right)}_2$ is heated, it produces Copper oxide$\left(\mathrm{CuO}\right)$, Oxygen$\left({\mathrm{O}}_2\right)$, and a brown-colored gas i.e., Nitrogen dioxide$\left({\mathrm{NO}}_2\right)$.
3. The chemical equation can be written as:

$$\begin{gathered} 2\mathrm{Cu}{\left({\mathrm{NO}}_3\right)}_2\left(\mathrm{s}\right)\stackrel{\mathrm{heat}}{\to }2\mathrm{CuO}\left(\mathrm{s}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)+4{\mathrm{NO}}_2\left(\mathrm{g}\right) \\ (\mathrm{Copper}\mathrm{nitrate})(\mathrm{Copper}\mathrm{oxide})\left(\mathrm{Oxygen}\right)(\mathrm{Nitrogen}\mathrm{oxide}) \end{gathered}$$

4. The mass of reactant is the same as the mass of products here, Hence, the chemical equation is balanced.

5. All the atoms are balanced in this equation, hence, it follows the law of conservation of mass.