Question

The molality of calcium chloride (CaCl2) in an aqueous solution is 2.46 m. What is mole fraction of the solute?

Answer 1

Given that CaCl2 = 2.46 m

Therefore 2.46 mole of CaCl2 present in 1.00 g of solution

Mass of 2.46 mole CaCl2= number of mole * molar mass

= 2.46 mole  * 110.98 g/mol

= 273.01 g

Mass of water or solvent = mass of solution – mass of solute  

= 1000 g -273.01 g

= 726.99 g

Mole of water = amount in g / molar mass

= 726.99 g/18.02 g/ mole

= 40.34 moles

Mole fraction of CaCl2 = number of mole of CaCl2 / total moles

= 2.46 /2.46+40.34

= 2.46/42.8

= 0.057