Question

Illustrate the law of conservation of mass with an example.

Answer 1

Definition:

The Law of conservation of mass states that “Mass in an isolated system can neither be created nor be destroyed but can be transformed from one form to another". In simple terms, this law states that matter can neither be created nor destroyed. The total mass of reacting mixture and the products formed remains constant. Antoine Lavoisier gave this law in the year 1789.

Example: Formation of water

$2\left({\mathrm{H}}_2\right)+\hspace{0.17em}\left({\mathrm{O}}_2\right)=2\left({\mathrm{H}}_2\mathrm{O}\right)$

Atomic mass of hydrogen = 1 u

Atomic mass of oxygen = 16 u

The total mass of reactants = $(2\times 2)+(2\times 16)=36$g

The total mass of products = $2\times (2+16)=2\times 18=36$g