Question

Complete and balance the following equation:

$\mathrm{CuO}+\mathrm{HCl}(dil\mathit{.})\to$

Answer 1

• When metallic oxide reacts with Hydrochloric acid ($\mathbf{HCl}$) it forms its respective Chloride along with water.
• General reaction between Metal oxide and Hydrochloric acid is given below :

$$\begin{gathered} \mathrm{Metal}+\mathrm{Hydrochloric}\to \mathrm{Metal}+\mathrm{Water} \\ \mathrm{oxide}\mathrm{acid}(dil\mathit{.})\mathrm{chloride} \end{gathered}$$

Step 1: Reacting the given molecules:

• Copper(II) oxide ($\mathbf{CuO}$) react with Hydrogen chloride ($\mathbf{HCl}$) it produces Copper(II) chloride (${\mathbf{CuCl}}_{\mathbf{2}}$) and water.
• Complete reaction between Copper (II) Oxide $\left(\mathrm{CuO}\right)$ and Hydrochloric acid $\left(\mathbf{HCl}\right)$ is $\underset{(\mathrm{Copper}(\mathrm{II})\mathrm{oxide})}{\mathrm{CuO}\left(s\right)}+\underset{(\mathrm{Hydrochloric}\mathrm{acid})}{\mathrm{HCl}\left(aq\right)}\to \underset{(\mathrm{Copper}(\mathrm{II})\mathrm{Chloride})}{{\mathrm{CuCl}}_2\left(aq\right)}+\underset{\left(\mathrm{Water}\right)}{{\mathrm{H}}_2\mathrm{O}\left(aq\right)}$

Step 2: Balancing the chemical equation

• The obtained chemical reaction is unbalanced, to balance it we first count the number of molecules on both sides of the reaction.
• On the reactant side: 1 Copper and 1 Oxygen are present in the Copper oxide.
• Similarly, 1 Hydrogen and 1 Chlorine are present in Hydrogen chloride.
• On the product side: 1 Copper and 2 Chlorine are present in Copper chloride
• Similarly, 2 Hydrogen and 1 oxygen are present in the water molecule.

Step 3: Balancing the reactant molecules by multiplying 2 by Hydrogen chloride.

• The chemical reaction is as follows: $\underset{(\mathrm{Copper}\mathrm{oxide})}{\mathrm{CuO}\left(s\right)}+\underset{(\mathrm{Hydrogen}\mathrm{chloride})}{2\mathrm{HCl}\left(aq\right)}\to \underset{(\mathrm{Copper}\mathrm{chloride})}{{\mathrm{CuCl}}_2\left(aq\right)}+\underset{\left(\mathrm{Water}\right)}{{\mathrm{H}}_2\mathrm{O}\left(aq\right)}$
• Therefore, after multiplication we have an equal number of molecules on both sides of the reaction.

Step 4: Balanced chemical equation is as follows:

• The balanced chemical equation: $\underset{(\mathrm{Copper}\mathrm{oxide})}{\mathrm{CuO}\left(s\right)}+\underset{(\mathrm{Hydrogen}\mathrm{chloride})}{2\mathrm{HCl}\left(aq\right)}\to \underset{(\mathrm{Copper}\mathrm{chloride})}{{\mathrm{CuCl}}_2\left(aq\right)}+\underset{\left(\mathrm{Water}\right)}{{\mathrm{H}}_2\mathrm{O}\left(aq\right)}$
• The total number of molecules on both sides of the reaction is equal i.e. on the reactant and product side.
• On the reactant side: 1 Copper and 1 Oxygen are present in the Copper oxide.
• Similarly, 2 Hydrogen and 2 Chlorine are present in Hydrogen chloride.
• On the product side: 1 Copper and 2 Chlorine are present in Copper chloride
• Similarly, 2 Hydrogen and 1 oxygen are present in the water molecule.

Hence the balanced chemical equation is $\underset{(\mathrm{Copper}\mathrm{oxide})}{\mathrm{CuO}\left(s\right)}+\underset{(\mathrm{Hydrogen}\mathrm{chloride})}{2\mathrm{HCl}\left(aq\right)}\to \underset{(\mathrm{Copper}\mathrm{chloride})}{{\mathrm{CuCl}}_2\left(aq\right)}+\underset{\left(\mathrm{Water}\right)}{{\mathrm{H}}_2\mathrm{O}\left(aq\right)}$