Question

A 1.2 m aqueous solution of an ionic compound with the formula MX2 has a boiling point of 101.4 celsisus. Calulate the van't Hoff factor i for MX2 at this concentration

Answer 1

The boiling point increase of a solution is a colligative property, which means that it is related with the solvent and the concentration of the solute, as per this formula:

ΔT = i * kb * m

Where, ΔT is the increase in the boiling point, i is the van't Hoof factor (which accounts for the numberof particles that are dissolved), kb is the boiling point and m the molality of the solution.

Gvien the normal boiling point of 100°C for pure water, ΔT = 101.4 °C - 100.0 °C = 1.4 °C.

Kb = 0.512 °C / m

m = 1.2 m

Therefore, i = ΔT / (kb * m) = 1.4°C / (0.512 °C/m * 1.2m) = 2.28

Answer: 2.28