Question

A solution is made by dissolving 3.8 moles of sodium chloride (NaCl) in 185 grams of water. If the molal boiling point constant for water (Kb) is 0.51 °C/m, what would be the boiling point of this solution? Show all of the work needed to solve this problem.

Answer 1

The molality of the solution can be defined as moles of solute per kilogram of solvent.

Molality=3.8 moles/0.185 kg

=20.54 molal

The change in the temperature can be calculated as the product of boiling point constant and molality.

ΔTb=Kb×m=0.51 °C/m×20.54 m=10.47 °C.

The boiling point of the solution will be = 100 °C + 10.47 °C

=110.47 °C