In the lab, a student follows the following steps to determine the freezing point and molality of a deicer solution.
1. Measured the mass of calorimeter with stir bar.
2. Measured the mass of deicer.
3. Measured the volume of water and transfered it to the calorimeter.
4. Added the deicer to calorimeter and dissolved it in the water.
5. Measured the mass of the calorimeter with its contents.
6. Added ice to the calorimeter and reweigh it.
7. Placed a lid on the calorimeter, monitored the temperature of the solution, and recorded the freezing temperature.
8. Decanted the deicer solution, keeping the stir bar and remaining ice. Then measured the mass of the calorimeter with its remaining contents.
Trial 1
Freezing temperature of deionized water: 0.02°C
Deicer used (chemical formula): KCl
Mass of calorimeter + stir bar: 12.74 g
Mass of deicer: 5.50 g
Volume of water: 58.6 mL
Mass of calorimeter, stir bar, deicer, and water: 76.84 g
Mass of calorimeter, stir bar, deicer, water, and added ice: 126.97 g
Mass of calorimeter, stir bar, and remaining ice: 65.10 g
Minimum temperature reached: -4.75°C
(a) Using the data from the table, determine the molality of the deicer solution.
molality = m KCl
(b) Based on the collected data, what is the van't Hoff factor? The Kf for water is 1.86 °C/m.
i =