Week 16
Monday 1-2-12
No School
Tuesday 1-3-12
Does Temperature Affect Dissolving?
Key Concepts

•Adding energy (heating) increases molecular motion.

•Increased molecular motion competes with the attraction between solute molecules and tends to make them come apart more easily.

•Increased molecular motion causes more solvent molecules to contact solute molecules and pull on them with more force, usually resulting in more dissolving.

•Since different substances are made from different atoms, ions, or molecules, increased temperature will affect their dissolving to different extents.

Summary

Students revisit the dissolving M&M activity from Lesson 4. They will design an experiment to see if temperature affects the amount of dissolving of the sugar coating of an M&M.

Objective

Students will be able to identify and control variables to design an experiment to see whether the temperature of a solvent affects the speed at which a solute dissolves. Students will be able to explain, on the molecular level, why increasing temperature increases the rate of dissolving.

Materials for Each Group

•M&M's (3 same color)

•3 clear plastic cups

•1 sheet of white paper

•Room-temperature water

•Hot water (about 50 °C)

•Cold water (about 5 °C)

*** Quick demo with dissolving of M&Ms in water, alcohol and oil.

Have students work in groups to design an experiment to investigate whether the temperature of water affects the amount of M&M coating that dissolves.

What could you investigate about M&M’s dissolving in water?

How could you investigate whether the temperature of water affects the amount of coating that dissolves from an M&M?

What are the variables in this experiment, and how will you control them?

*** Students write up laboratory procedure today

Wednesday, 1-4-12

***Students conduct laboratory procedure today.

Thursday 1-5-12

Friday, 1-6-12