A solution will boil at a higher temperature than the pure solvent. This is the colligative property called boiling point elevation.
An equation has been developed for this behavior. It is:
Δt = i × Kb × m
Δt = the boiling point elevation
Kb for water is 0.512°C kg mol¯1
i = 1 (for non-volatile electrolyte)
m = the molality of the solute
The boiling point of pure water is 100°C.
Δt = 100.75°C - 100.00°C = 0.75°C
Δt = 0.75°C
m = Δt / (i × Kb) = (0.75°C) / (1 × 0.512°C kg mol¯1) = 1.4648 mol/kg = 1.465 mol/kg
m = 1.465 mol/kg
The boiling point elevation (Δt) is 0.75°C
The molality of the solution (m) is 1.465 mol/kg