Activity Overview
Investigate the freezing point depression due to different concentration of solute.
Objectives
Experimentally determine the relationship between molality and freezing point.
Experimentally determine the freezing-point depression constant for water.
Calculate variations in freezing point due to dissolved substances.
About the Lesson
The following questions will guide student exploration during this activity:
How does the concentration of a solute affect the freezing point of a solution?
How do solutes affect colligative properties?
In this activity, students first observe the freezing points of various aqueous sucrose solutions. They observe that the freezing point decreases as solute concentration increases. They use linear regression to estimate the freezing-point depression constant for water. Then, they use the accepted theoretical freezing-point depression constant to calculate the freezing points of various solutions.