Question

calculate the mass percent of different element in soddium sulphate (Na2So4)

Answer 1

142g
sodium2×23=46g
sulphur=32g
oxygen=4×16=64g
46+32+64=142g

Answer 2

Molar mass of Na2SO4 = [(2 × 23.0) + (32.00) + 4 (16.00)] = 142 g

Mass percent of an element = (Mass of that element in compound/Molar mass of that compound) × 100

∴ Mass percent of sodium (Na): (46/142) × 100 = 32.39%

Mass percent of sulphur(S): (32/142) × 100 = 22.54%
Mass percent of oxygen:(O): (64/142) × 100 = 45.07%