Chapter 3 Resource: Matter and its Changes

Name Date Class
1
Enrichment
Freezing Points of Solutions
The physical properties of a solution are somewhat different than the physical properties of the
solvent and the solute that make up the solution. In this activity, you will determine how the addition
of a solute to a solvent affects the solvent’s freezing point. (Water will be the solvent, and
alcohol will be the solute.)
Materials
masking tape
water
marker
rubbing alcohol
plastic cups (3) toothpick
measuring spoons
Procedure
1. Use pieces of masking tape to label three
cups 100% water, 75% water, and 50% water.
2. Add 2 teaspoons of water to the 100%
water cup.
3. Add 1 1/2 teaspoons of water and 1/2 teaspoon
of rubbing alcohol to the 75% water cup.
Data and Observations
Table 1
4. Add 1 teaspoon of water and 1 teaspoon of
rubbing alcohol to the 50% water cup.
Then place the cups in a freezer.
5. After 10 minutes, check on the cups, and
record your observations in the table below.
Poke the ice with a toothpick to determine
whether the contents have frozen solid.
6. Repeat step 5 three more times. Add your
observations to the data table.
7. After you finish, discard all three cups.
Rubbing alcohol should be discarded in an
appropriate waste container.
Meeting Individual Needs
Time
100% Water
75% Water
50% Water
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
10 minutes
20 minutes
30 minutes
40 minutes
Questions and Conclusions
1. Which liquid had the highest freezing point Which had the lowest How do you know
2. Based on your results, what is the relationship between the amount of solute and the freezing
point of the solution
3. Many types of windshield wiper fluid are water-based solutions that contain a type of alcohol
called methanol. What is one likely reason that methanol is added to these fluids
Matter and Its Changes 29