Question

How will you calculate the molecular mass?

Answer 1

Definition of Molecular Mass:

1. The sum of atomic masses of all the atoms in a molecule is known as the molecular mass.
2. Molecular mass is expressed as atomic mass unit $\left(\mathrm{u}\right)$.

Calculation of Molecular Mass:

1. Identify the type and number of all the atoms in the molecule.
2. Add the atomic masses of all the atoms.

Example:

1. The molecular formula of water is $\mathbf{\left(}{\mathbf{H}}_{\mathbf{2}}\mathbf{O}\mathbf{\right)}$.
2. The molecular mass of water, having two hydrogen $\mathbf{\left(}\mathbf{H}\mathbf{\right)}$ atoms and one oxygen $\mathbf{\left(}\mathbf{O}\mathbf{\right)}$ atom is $=(2\times 1\mathrm{u})+(1\times 16\mathrm{u})=(2+16)\mathrm{u}=18\mathrm{u}$.
3. Thus, the molecular mass of water is $\mathbf{18}\mathbf{u}$.