Question

The molality of calcium chloride (CaCl2) in an aqueous solution is 3.37 m. What is mole fraction of the solute? Keep 3 significant figures in your answer.

Answer 1

mole fraction of the solute = 0.0572

Explanation

molality of CaCl₂ = 3.37 m

This means 3.37 moles of CaCl₂ is dissolved in 1 kg water

mass of water = 1kg = 1000 g

moles of water = (mass of water) / (molar mass of water)

moles of water = (1000 g) / (18.0 g/mol)

moles of water = 55.5 mol

Total moles = moles CaCl₂ + moles of water

Total moles = 3.37 mol + 55.5 mol

Total moles = 58.9 mol

mole fraction of CaCl₂ = (moles of CaCl₂) / (total moles)

mole fraction of CaCl₂ = (3.37 mol) / (58.9 mol)

mole fraction of CaCl₂ = 0.0572