Question

Define molecular mass of a substance?

Answer 1

Molecular mass:

• The molecular mass of a substance is the relative mass of its molecule as compared to the mass of the Carbon-12 atom taken as 12-units.
• Molecular mass is the total mass of a compound.
• It is equal to the sum of the atomic masses or mass numbers of each element present in a compound or molecule.

Calculation of molecular mass:

For example, calculation of the molecular mass of sodium hydroxide (NaOH):

• Mass number of sodium( Na) = 23
• Mass number of oxygen is (O) = 16
• Mass number of hydrogen is (H) = 1
• On adding the mass number of all the elements present in the formula we can calculate the molecular mass of the compound.
• So, molecular mass of sodium hydroxide is 23 + 16 + 1 = 40