Question

Calculate the mass percent of different elements present in sodium sulphate ($Na_{2}SO_{4}$).

Answer 1

To calculate the mass of the individual elements present in sodium sulphate $Na_{2}SO_{4}$, one mole of sodium sulphate is taken. Sodium sulphate contains two moles of sodium, one mole of sulphur, and 4 moles of oxygen. The mass percentage of the elements are as follows

Molecular weight of sodium sulphate = 142 grams  

2 moles of sodium (Na) = 2 x 23 grams = 46 grams  

One mole of sulphur (S) = 32 grams

4 moles of oxygen (O) = 4 x 16 grams = 64 grams

Mass Percentage,

Sodium = $\frac{46}{142} \times 100$ = 32.39%

Sulphur = $\frac{32}{142} \times 100$ = 22.53%

Oxygen = $\frac{64}{142} \times 100$ = 45.06%