Question

State the law of conservation of mass. Give one example to illustrate this law.

Answer 1

The law of conservation of mass states that the mass of a closed system will remain constant in a chemical reaction. In other words, The mass in an isolated system can neither be created nor be destroyed but can be transformed from one form to another. This law was first formulated by Antoine Laurent Lavoisier in 1789.
For example: When 100g of mercuric oxide is heated, 92.6 g of mercury and 7.4 g of oxygen are obtained as products.
i.e. $Hg⟶Hg+O_2$
In this case mass of reactant =100g
Mass of products = Mass of Hg + Mass of $o_2$= 92.6 + 7.4 = 100g
Hence, Mass of product = Mass of reactants
This verifies the law of conservation of mass.