Question

4) Determine the molality of a solution prepared by dissolving 0.500 moles of CaF2 in 11.5 moles H2O.

A) 1.88 m

B) 4.35 m

C) 5.31 m

D) 4.14 m

E) 2.41 m

Answer 1

4) molality = no. of moles of solute / weight of solvent in kg

weight of solvent = no. of moles x molecular mass = 11.5 x 18 = 207 g = 0.207 kg

no. of moles of solute = 0.5 moles

therefore; molality = 0.5 moles / 0.207 kg = 2.415 m

correct answer is E) 2.41 m