Question

State law of constant proportions.

Answer 1

Hint: The law of constant proportions was given in 1779 by Joseph Proust, a French chemist. The law of constant proportions in a simple way can be expressed as in any chemical substance, the elements are always present in a definite proportion by mass.

Complete step-by-step solution:
In chemical compounds, the elements are present in a fixed ratio by mass. This is the “law of constant proportions''. This “law of constant proportions” is also termed as the law of definite proportions or as the Proust’s law. For example, pure water contains oxygen and hydrogen in a fixed ratio of 1:8. Water contains 0.88 grams of oxygen and 0.12 grams of hydrogen.

Additional information:
The law of constant proportions has many exceptions such as compounds like wustite, which is an iron oxide having chemical formula FeO, the ratio of iron atom and the oxygen atom may range from 0.83:1 to 0.95:1. It follows the law of multiple proportions.

Note: Students may get confused between the law of constant proportions and the law of multiple proportions. Law of constant proportion states that, in chemical compounds, the elements are present in a fixed ratio by mass. When two same elements combine together forming more than just one compound, the ratio of the mass of one element in the first compound and the mass in the second compound, can be always expressed as a ratio of small whole numbers.