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Ideal for grades 10-12, in this lesson, students will investigate how solutes affect the colligative properties of solutions, specifically freezing point depression and boiling point elevation. Colligative properties are related to the ratio of solute particles to solvent particles. Students will calculate the molality of various solutions as they conduct an experiment to determine the effect of two solutes, an ionic compound and a molecular compound, on the
boiling point of water.

After completing this lesson, students will understand:

• How solutes affect the colligative properties of solutions using freezing point depression and boiling point elevation.

Resources included:

• Lesson plan
• Student experiment worksheet

Additional resources required:
Per Student:

• safety goggles
• data sheet
• calculator
• pencil
• graph paper

Per Group:

• periodic table
• alcohol or digital thermometer
• hot plate
• magnetic stirrer
• 3 × 1.0 L beaker (glass, lab grade)
• oven mitts

Shared by Class:

• balance
• plastic weighing dishes
• distilled water (or tap water)
• sodium chloride
• sucrose