# Question #bed9f

Jun 18, 2015

${\text{Zn" +2"HCl" -> "ZnCl"_2 + "H}}_{2}$

#### Explanation:

The method I find useful when it comes to balancing a chemical equation is to draw a chart corresponding to the number of moles: (Split compounds into one unit of its own but, for polyatomic count them as one whole unit)

Unbalanced chemical equation:

${\text{Zn " + " HCl" -> "ZnCl"_2 + "H}}_{2}$

The reason you need to balance a chemical equation is because energy is conserved throughout the chemical process.

Reactant side:

• $\text{Zn} = 1$
• $\text{H} = 1$
• $\text{Cl} = 1$

Product side:

• $\text{Zn} = 1$
• $\text{H} = 2$
• $\text{Cl} = 2$

You need two hydrogens and two chlorines on the left and right sides, so multiply $\text{HCl}$ by $2$

Reactant side:

• $\text{Zn} = 1$
• $\text{H" =1 xx 2 = "2 moles of H}$
• $\text{Cl" = 1 xx 2 = "2 moles of Cl}$

Product side:

• $\text{Zn} = 1$
• $\text{H} = 2$
• $\text{Cl} = 2$

The balanced chemical equation:

${\text{Zn" + 2"HCl" -> "ZnCl"_2 + "H}}_{2}$