Question

What is molecular mass ? Calculate the molecular mass of sodium chloride and water.

Answer 1

Molecular mass: The molecular mass of a substance is the sum of the atomic masses of all the atoms present in a molecule of that substance. This is also called the relative molecular mass and its unit is atomic mass unit (u). Hence, to calculate the mass of molecules i.e. to calculate the molecular mass, the mass of all the atoms present in it are added.

• Molecular mass of NaCl = Molar mass of Na + molar mass of Cl

= (23+ 35.5) g

= 58.5 g

• Molecular mass of H₂O = Molar mass of H + molar mass of O

= ( 2*1) + 16

=18g