1. Solve for the Molality of NH3(aq)
Molality (molal) is in units of moles of solute per kilograms of solvent. Ammonia is the solute and water is the solvent.
1a. Calculate Moles Solute (NH3)
1b. Calculate Kilograms Solvent (H2O)
1c. Calculate Molality NH3(aq)
2. Solve for the Freezing Point of the Solution [NH3(aq)]
2a. Calculate the Decrease in Freezing Point
The decrease in freezing point is equal to the van’t Hoff factor multiplied by the molal freezing-point depression constant for water and the molality of ammonia solute particles in water.
2b. Calculate the Freezing Point of the Solution
The freezing point of the solution is equal to the difference between the normal freezing point of pure water and the decrease in freezing point value.