Question

State the law of constant proportions. Give one example to illustrate this law.

Answer 1

Law of constant proportions states that a chemical compound always consists of the same elements combined together in the same proportion by mass. It was put forward by Joseph Proust in 1779
It means that a pure chemical compound is always made up of the same elements in the same mass percentage.

Law of constant proportions can be illustrated by the following example:

Carbon dioxide exists in nature in different forms and can be chemically produced in different ways. Yet, all the different samples of carbon dioxide will always contain the same elements i.e. carbon and oxygen in the same proportion by mass i.e. 3:8.