Question

Deduce the molecular masses of the given compounds:-

Molecular formulae- HNO3, AlCl3,

[Atomic masses- H=1,O=16, N=14,Cl=35.5]​

Answer 1

Answer:

The molecular mass of HNO3 is 63 u and that of AlCl3 is 133.5 u

Given,

Atomic mass of Hydrogen = 1 u

Atomic mass of Oxygen = 16 u

Atomic mass of Nitrogen = 14 u

Atomic mass of Chlorine = 35.5 u

We know that,

Atomic mass of Aluminium = 27 u

Also, the molecular mass of any compound is the sum of the atomic masses of all the atoms present in that particular compound.

Solution

Molecular mass of HNO3 = Atomic mass of Hydrogen + Atomic mass of Nitrogen + 3×Atomic mass of Oxygen

= (1+14+3×16) u

= 63 u

Similarly, the molecular mass of AlCl3 = Atomic mass of Aluminium+ 3×Atomic mass of Chlorine

= (27+ 3×35.5) u

= 204.5 u

Hence the molecular mass of HNO3 is 63 u and the molecular mass of AlCl3 is 204.5 u