Question

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

Answer 1

Step1: Reacting to the given molecules:

• When Hydrochloric acid reacts with Zinc Hydroxide to form Zinc Chloride and water.
• The unbalanced chemical equation can be written as:
• $$\begin{gathered} \mathbf{Zn}{\mathbf{\left(}\mathbf{OH}\mathbf{\right)}}_{\mathbf{2}}\mathbf{}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}\mathbf{HCl}\mathbf{}\mathbf{\left(}\mathbf{aq}\mathbf{\right)}\mathbf{}\mathbf{\to }\mathbf{}{\mathbf{ZnCl}}_{\mathbf{2}}\mathbf{}\mathbf{\left(}\mathbf{aq}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}{\mathbf{H}}_{\mathbf{2}}\mathbf{O}\mathbf{}\mathbf{\left(}\mathbf{l}\mathbf{\right)} \\ \mathbf{}\mathbf{}\mathbf{}\mathbf{Zinc}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Hydrochloric}\mathbf{}\mathbf{}\mathbf{Zinc}\mathbf{} \\ \mathbf{Hydroxide}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{acid}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Chloride} \end{gathered}$$

Step 2: 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 $\mathbf{Zn}{\mathbf{\left(}\mathbf{OH}\mathbf{\right)}}_{\mathbf{2}}$, $\mathbf{2}$ Oxygen atoms from $\mathbf{Zn}{\mathbf{\left(}\mathbf{OH}\mathbf{\right)}}_{\mathbf{2}}$ $\mathbf{3}$ Hydrogen atoms from $\mathbf{1}$ Hydrogen atom from $\mathbf{HCl}$ and $\mathbf{2}$ Hydrogen atoms from $\mathbf{Zn}{\mathbf{\left(}\mathbf{OH}\mathbf{\right)}}_{\mathbf{2}}$ and $\mathbf{1}$ Chlorine atom from $\mathbf{HCl}$
• On the product side: $\mathbf{1}$ Zinc atom from ${\mathbf{ZnCl}}_{\mathbf{2}}$, $\mathbf{2}$ Chlorine atoms from ${\mathbf{ZnCl}}_{\mathbf{2}}$, $\mathbf{2}$ Hydrogen atoms from ${\mathbf{H}}_{\mathbf{2}}\mathbf{O}$ and $\mathbf{1}$ Oxygen atom from ${\mathbf{H}}_{\mathbf{2}}\mathbf{O}$.

Step 3: Balancing the reactant molecules by multiplying $\mathbf{2}$ by $\mathbf{HCl}$ and $\mathbf{2}$ by ${\mathbf{H}}_{\mathbf{2}}\mathbf{O}$.

• The chemical reaction is as follows:
• $$\begin{gathered} \mathbf{Zn}{\mathbf{\left(}\mathbf{OH}\mathbf{\right)}}_{\mathbf{2}}\mathbf{}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}\mathbf{2}\mathbf{}\mathbf{HCl}\mathbf{}\mathbf{\left(}\mathbf{aq}\mathbf{\right)}\mathbf{}\mathbf{\to }\mathbf{}{\mathbf{ZnCl}}_{\mathbf{2}}\mathbf{}\mathbf{\left(}\mathbf{aq}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}\mathbf{2}\mathbf{}{\mathbf{H}}_{\mathbf{2}}\mathbf{O}\mathbf{}\mathbf{\left(}\mathbf{l}\mathbf{\right)} \\ \mathbf{}\mathbf{}\mathbf{}\mathbf{Zinc}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Hydrochloric}\mathbf{}\mathbf{}\mathbf{Zinc}\mathbf{} \\ \mathbf{Hydroxide}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{acid}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Chloride} \end{gathered}$$
• On the reactant side: $\mathbf{1}$ Zinc atom from $\mathbf{Zn}{\mathbf{\left(}\mathbf{OH}\mathbf{\right)}}_{\mathbf{2}}$, $\mathbf{2}$ Oxygen atoms from $\mathbf{Zn}{\mathbf{\left(}\mathbf{OH}\mathbf{\right)}}_{\mathbf{2}}$ $\mathbf{4}$ Hydrogen atoms from $\mathbf{2}$ Hydrogen atom from $\mathbf{HCl}$ and $\mathbf{2}$ Hydrogen atoms from $\mathbf{Zn}{\mathbf{\left(}\mathbf{OH}\mathbf{\right)}}_{\mathbf{2}}$ 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 ${\mathbf{ZnCl}}_{\mathbf{2}}$, $\mathbf{4}$ Hydrogen atoms from ${\mathbf{H}}_{\mathbf{2}}\mathbf{O}$ and $\mathbf{2}$ Oxygen atom from ${\mathbf{H}}_{\mathbf{2}}\mathbf{O}$.
• After multiplication, we have an equal number of molecules on both sides of the reaction.

Step 4: Balanced chemical equation is as follows:

• Therefore the balanced equation is:
• $$\begin{gathered} \mathbf{Zn}{\mathbf{\left(}\mathbf{OH}\mathbf{\right)}}_{\mathbf{2}}\mathbf{}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}\mathbf{2}\mathbf{}\mathbf{HCl}\mathbf{}\mathbf{\left(}\mathbf{aq}\mathbf{\right)}\mathbf{}\mathbf{\to }\mathbf{}{\mathbf{ZnCl}}_{\mathbf{2}}\mathbf{}\mathbf{\left(}\mathbf{aq}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}\mathbf{2}\mathbf{}{\mathbf{H}}_{\mathbf{2}}\mathbf{O}\mathbf{}\mathbf{\left(}\mathbf{l}\mathbf{\right)} \\ \mathbf{}\mathbf{}\mathbf{}\mathbf{Zinc}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Hydrochloric}\mathbf{}\mathbf{}\mathbf{Zinc}\mathbf{} \\ \mathbf{Hydroxide}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{acid}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Chloride} \end{gathered}$$

Hence, the equation is balanced.