What is the Law of Conservation of Mass?

Law of Conservation of Mass is an important law for states that,

“For an isolated system mass can neither be created nor be destroyed but is easily transformed from one form to another”.

Law of conservation of mass in chemistry says the mass of the reactants at the beginning of the reaction is always equal to the mass of the products at the end of the reaction. The law of conservation of mass can easily be understood under two changes,

• Physical Changes
• Chemical Changes

When Matter Undergoes Physical Change

When the matter undergoes physical change the mass of the components as a whole system is always conserved. For example, take a piece of ice and place it in a flask properly close this flask and weigh it. Now, heat the flask gently to melt the ice into water and again weigh it.

Ice → (Heat)→ Water

The weight of the flask for and after heating is the same. This shows that when a matter undergoes physical change its mass is constant.

When Matter Undergoes Chemical Change

When any matter undergoes a chemical change the mass of the system remains unchanged. Swiss Chemist Hans Heinrich Landolt first explained this concept.

We can understand this concept with the help of the following chemical reaction,

NaCl (s) + AgNO₃ (aqueous) →  AgCl (s) + NaNO₃ (aqueous)

In the above chemical reaction sodium chloride reacts with silver nitrate to form silver chloride and sodium nitrate. The mass of the reactants and the mass of the product are the same in the above reaction.

Law of conservation of mass states that “The mass can neither be created nor destroyed in a chemical reaction” French chemist Antoine Lavoisier was the first to state the law of conservation of mass in his book. There is just a rearrangement in the atoms of substances for the formation of compounds.

In the chemical process, the law of conservation of mass can be understood as the total mass of the reactant at the beginning of the reaction being equivalent to the mass of the product at the end of the reaction. 

Mass _reactants = Mass _products

Let’s learn about the law of conservation of mass in detail in this article,