What Are Law Of Conservation Of Mass And Law Of Definite Proportion?

The earlier history of chemistry is full of worn out ideas about the changes that occur during a chemical reaction. It was the result of the efforts made by a French Chemist Antoine Lavoisier that these ideas were finally discarded and the chemistry was given its right direction. By making careful quantitative measurements, the scientist established that mass is neither created nor destroyed during a chemical change. He thus laid the foundation of the first law of chemistry, which was later called the law of conservation of mass. This law is defined as:    Mass is neither created nor destroyed during a chemical reaction but it only changes from one form to another form.

A book established by Lovioiser in 1789 encouraged scientists to study the quantitative relationship between reactants and the products. These investigations later on led to the formulation of second law of chemical combination named as definite proportions. Joseph Proust proved experimentally that a compound obtained from different sources will always contain the same elements obtained together in a fixed proportion. The law of definite proportion states:   When different elements combine to give a pure compound, the ratio between the masses of these elements will always remain the same.

We can get water from different sources like river, ocean, well, tube well and rain. If different samples of pure water obtained from these sources are analysed, we will always find the ratio between the masses of hydrogen and oxygen to be 1:8.