Question

Write the balanced chemical equation when Hydrochloric acid reacts with Zinc Oxide?

Answer 1

Step1: Reacting to the given molecules:

• The chemical formula of hydrochloric acid is $\mathbf{HCl}$. It reacts with Zinc Oxide ($\mathbf{ZnO}$) to form Zinc Chloride (${\mathbf{ZnCl}}_{\mathbf{2}}$) and water (${\mathbf{H}}_{\mathbf{2}}\mathbf{O}$)
• The unbalanced chemical equation can be written as $\mathbf{ZnO}\mathbf{}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{HCl}\mathbf{}\mathbf{\left(}\mathbf{l}\mathbf{\right)}\mathbf{\to }{\mathbf{ZnCl}}_{\mathbf{2}}\mathbf{}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{+}{\mathbf{H}}_{\mathbf{2}}\mathbf{O}\mathbf{\left(}\mathbf{l}\mathbf{\right)}$

Step2: Balancing the chemical equation

• The total number of atoms of each element on the reactant side and the product side must be compared.
• On the reactant side: $\mathbf{1}$ Zinc atom from $\mathbf{ZnO}$, $\mathbf{1}$ Oxygen atom from $\mathbf{ZnO}$ $\mathbf{1}$ Hydrogen atom from $\mathbf{HCl}$ and $\mathbf{1}$ Chlorine atom from $\mathbf{HCl}$
• On the product side: $\mathbf{1}$ Zinc atom from ${\mathbf{ZnCl}}_{\mathbf{2}}$, $\mathbf{2}$ Cl atoms from ${\mathbf{ZnCl}}_{\mathbf{2}}$, $\mathbf{2}$ Hydrogen atoms from ${\mathbf{H}}_{\mathbf{2}}\mathbf{O}$ and $\mathbf{1}$ Oxygen atom from ${\mathbf{H}}_{\mathbf{2}}\mathbf{O}$.

Step3: Balancing the reactant molecules by multiplying 2 by $\mathbf{HCl}$

• The chemical reaction is as follows: $\mathbf{ZnO}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{+}\mathbf{HCl}\mathbf{\left(}\mathbf{l}\mathbf{\right)}\mathbf{\to }{\mathbf{ZnCl}}_{\mathbf{2}}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{}\mathbf{+}{\mathbf{H}}_{\mathbf{2}}\mathbf{O}\mathbf{\left(}\mathbf{l}\mathbf{\right)}$
• $\mathbf{Zinc}\mathbf{}\mathbf{oxide}\mathbf{}\mathbf{+}\mathbf{}\mathbf{Hydrochloric}\mathbf{}\mathbf{Acid}\mathbf{\to }\mathbf{}\mathbf{Zinc}\mathbf{}\mathbf{Chloride}\mathbf{}\mathbf{+}\mathbf{}\mathbf{Water}$
• After multiplication, we have an equal number of molecules on both sides of the reaction. equation is $\mathbf{ZnO}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}\mathbf{2}\mathbf{HCl}\mathbf{\left(}\mathbf{l}\mathbf{\right)}\mathbf{}\mathbf{\to }{\mathbf{ZnCl}}_{\mathbf{2}}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}{\mathbf{H}}_{\mathbf{2}}\mathbf{O}\mathbf{\left(}\mathbf{l}\mathbf{\right)}$

Step4: Balanced chemical equation is as follows:

• The chemical reaction is as follows: $\mathbf{ZnO}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}\mathbf{2}\mathbf{HCl}\mathbf{\left(}\mathbf{l}\mathbf{\right)}\mathbf{}\mathbf{\to }{\mathbf{ZnCl}}_{\mathbf{2}}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}{\mathbf{H}}_{\mathbf{2}}\mathbf{O}\mathbf{\left(}\mathbf{l}\mathbf{\right)}$
• On the reactant side: $\mathbf{1}$ Zinc atom from $\mathbf{ZnO}$, 2 Hydrogen atoms from $\mathbf{HCl}$ and $\mathbf{2}$ Chlorine atom from $\mathbf{HCl}$
• On the product side: $\mathbf{1}$ Zinc atom from ${\mathbf{ZnCl}}_{\mathbf{2}}$, $\mathbf{2}$ Chlorine atoms from ${\mathbf{ZnCl}}_{\mathbf{2}}$ and $\mathbf{2}$ Hydrogen atoms from ${\mathbf{H}}_{\mathbf{2}}\mathbf{O}$ and $\mathbf{1}$ Oxygen atom from ${\mathbf{H}}_{\mathbf{2}}\mathbf{O}$

Hence, the equation is balanced.