Question

What is a balanced chemical equation? How would you use the law of conversion of mass to explain why a chemical equation must be balanced?

Answer 1

Hint: A chemical equation represents the conversion of reactant into product. The chemical equation represents the chemical formula of the reactant on the left side of an arrow and the chemical formula of the product on the right side of the arrow. Law of conversion of mass explains that the total mass of the compounds remains the same. Only the forms of compounds change.

Complete step by step answer:
When two chemical compounds react they form some other compounds. The reacting compounds are known as reactants and the formed compounds are known as products. The whole action is defined as a chemical reaction. The representation of a chemical reaction in form of the chemical formula of each species is known as a chemical equation.
For example, we can consider hydrogen reacts with chlorine to form hydrogen chloride.

The chemical equation between hydrogen and chlorine is shown as follows:
${{\text{H}}_2}\, + \,{\text{C}}{{\text{l}}_{\text{2}}}\,\, \to \,\,{\text{HCl}}\,$
The above reaction is not balanced. The mass of hydrogen is $2.0$ ($1.0 \times 2$) and chlorine is $70.9$($35.45 \times 2$), so the total mass of the reactant is $72.9$. The mass of HCl is $36.45$. So, the total mass of the reactant is not equal to the total mass of the product.

The balanced reaction is as follows:
${{\text{H}}_2}\, + \,{\text{C}}{{\text{l}}_{\text{2}}}\,\, \to \,2\,{\text{HCl}}\,$
The total mass of the product is $72.9$($36.45 \times 2$) , so the mass of the product is equal to the mass of the reactant.
Therefore, to follow the law of conversion of mass, a chemical equation must be balanced.

Note: Simply, a chemical equation includes reactants, products with their state if known, and an arrow pointing from reactant to products which shows the conversion of reactant into the product. A balanced reaction and atoms is present in the same number on both sides of the reaction. The total mass of an atom becomes equal on both sides in a balanced reaction. We do not balance the catalyst which is used in a chemical reaction. Sometimes energy is also released with the product.