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

part -1 

 part -2 

 Method - 1

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