1.2 Calculate the mass per cent of different elements present in sodium sulphate (Na2SO4).

The molecular formula of sodium sulfate is Na2SO4.
Molar mass of Na2SO4 = [(2 × 23.0) + (32.066) + 4 (16.00)]
= 142.066 g

The mass percent of an element = MassofthetelementinthecompoundMolarmassofthecompound×100
 The mass percent of sodium:

=46.0g142.066×100
=32.379
=32.4%

The mass percent of sulphur:

=32.066g142.066×100
=22.57
=22.6%

The mass percent of oxygen:

=64.0g142.066×100
=45.049
=45.05%