Find out the mole fraction of solute in an aqueous solution of 30% NaOH

30% NaOH means 100g of solution contains 30g of NaOH

Mass of water in solution = 100 – 30 = 70g

Molar mass of NaOH = 40 g

Mass of NaOH = 30 g

Molar mass of water = 18 g

Mass of water given = 70g

Number of moles of NaOH = 30/40 = 0.75 moles

Number of moles of H2O = 70/18 = 3.88 moles

Total moles= 0.75+3.88 =4.63

therefore Molefraction of NaOH = NO: of moles of NaoH/Total moles

= 0.75/4.63 = 0.16

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