Question

What is the molecular mass of ${\mathrm{Na}}_2{\mathrm{SO}}_4$?

Answer 1

Step1. Molecular mass

• Molecular mass or molecular weight is the mass of a molecule.
• It is calculated as the sum of the atomic mass of each constituent element multiplied by the number of atoms of that element in the molecular formula.

Step2. The formula for molecular mass of ${\mathrm{Na}}_2{\mathrm{SO}}_4$

The molecular mass of ${\mathrm{Na}}_2{\mathrm{SO}}_4$ =$(2\times \text{Atomic mass of Na+}\mathrm{Atomic}\mathrm{mass}\mathrm{of}\text{S}+4\times \mathrm{Atomic}\mathrm{mass}\mathrm{of}\text{O)}$

Step3.Calculation of molecular mass of ${\mathrm{Na}}_2{\mathrm{SO}}_4$

The molecular mass of${\mathrm{Na}}_2{\mathrm{SO}}_4$ =$\left(2\times \text{22.99+32.06}+4\times 16.00\right)\text{u}$

=$\left(45.98+32.06+64\right)\text{u}$

=$142.04\text{u}$

Hence, the molecular mass of ${\mathrm{Na}}_2{\mathrm{SO}}_4$ is $142.04\text{u}$.