|Class 9 Chemistry Atoms and Molecules||Molecular mass|
Molecular mass of a substance is defined as the sum o the atomic masses of all the atoms present in a molecule of a substance. Therefore the relative mass of a molecule is expressed as atomic mass units (amu).
Let us calculate the molecular mass of H2O. we will find it out by following process.
2 X 1 + 1 X 16 = 18u