Question

Observe the reaction: $\text{Zinc + Hydrochloric acid}\to \text{Zinc chloride + Hydrogen}$
Select the correct balanced chemical equation from the follwoing options.

• A. $Zn\left(s\right)+2HCl\left(aq\right)\to ZnC{l}_2\left(aq\right)+H_2\left(g\right)$
• B. $Zn\left(s\right)+HCl\left(aq\right)\to ZnCl\left(aq\right)+H_2\left(g\right)$
• C. $Zn\left(s\right)+2HCl\left(aq\right)\to 2ZnC{l}_2\left(aq\right)+H_2\left(g\right)$
• D. $Zn\left(s\right)+HCl\left(aq\right)\to ZnC{l}_2\left(aq\right)+H_2\left(g\right)$

Answer 1

The correct option is A $Zn\left(s\right)+2HCl\left(aq\right)\to ZnC{l}_2\left(aq\right)+H_2\left(g\right)$

The chemical equation for this reaction is given below:
$\text{Zn}\text{(s)}+\text{HCl}\text{(aq)}\to {\text{ZnCl}}_2\left(aq\right)+{\text{H}}_2\text{(g)}$

We can see that: Reactants Products

Elements	No. of atoms	Elements	No.of atoms
Zn	1	Zn	1
H	1	H	2
Cl	1	Cl	2

Here, the number of H and Cl atoms on the reactant side equals to 1, whereas on the product side, the number equals to 2.

Now in order to balance the equation, the number of atoms on both reactants and the products side should be equal. If we write a coefficient '2' before HCl on the reactant side, the number of atoms of each element becomes same on both reactant and product side.

Thus, the balanced chemical equation is:
$\text{Zn}\text{(s)}+\text{2HCl}\to {\text{ZnCl}}_2\left(aq\right)+{\text{H}}_2\text{(g)}$