Question

How do chemical equations demonstrate the conservation of mass?

Answer 1

Matter can neither be created nor be destroyed in chemical reactions. This is the law of conservation of mass. Balanced chemical equations show that mass is conserved in chemical reactions. We will show how chemical reactions follow the law of conservation of mass with the help of an example.

Complete answer:
In every chemical reaction, the same amount of matter must end up in the products as started in the reactants. In other words, we can say that the mass of the products in a chemical reaction must equal the mass of reactants. Thus, there is no change in mass in a physical change or chemical reaction. This is because no atoms are created or destroyed during chemical reactions. The number and type of atoms does not change in a chemical reaction. Only a balanced chemical reaction follows the law of conservation of mass.
Demonstrating law of conservation of mass with the help of a balanced chemical reaction:
${N_2}(g)\, + 3{H_2}(g) \to 2N{H_3}(g)$
No extra mass is created in this reaction and hence this reaction is an example of law of conservation of mass as this is a balanced chemical reaction.

Note: There are five laws of chemical combination- law of conservation of mass, law of constant composition or definite proportions, law of multiple proportions, law of reciprocal proportions and Gay Lussac’s law of combining volumes. The first four deals with the mass relationships while the last one deals with the volumes of the gases both among the reactants and products.