Question

find out the mole fraction of 30% aqueous solution of sodium carbonate.

Answer 1

Let the total mass of solution be 100g
Mass of sodium carbonate = 30g
Mass of water = 100 - 30 = 70 g

Moles of Na₂CO₃ = 30/106 = 0.28 g/mol
​Moles of water = 70/18 = 3.89 mol

​Mole fraction of sodium carbonate = moles of sodium carbonate/ (moles of sodium carbonate + moles of water)

= 0.28/(0.28 + 3.89)
=0.28/4.17 = 0.067