Question

The mass of one molecule of a substance is 4.65 × 10–23 g. What is its molecular mass ? What could this substance be ?

Answer 1

Given:

Mass of one molecule of a substance = 4.65 × 10^-23

We know that the mass of a molecule of a substance is equal to the mass of 1 mole of that substance. 1 mole of a substance consists of 6.022 × 10²³ molecules; therefore, the mass of a molecule of a substance is equal to the mass of 6.022 × 10²³ molecules.

Therefore, to calculate the molecular mass of the substance, we need to calculate the mass of 6.022 × 10²³ molecules of that substance.

Mass of 1 molecule of the substance = 4.65 × 10^-23

Mass of 6.022 × 10²³ molecules of the substance = 6.022 × 10²³ × 4.65 × 10^-23 = 28g

Hence, molecular mass of the substance is 28 u.

Nitrogen has a molecular mass of 28 u; therefore, the substance is nitrogen.