EXPERIMENT 4.2

PURPOSE:

To observe the differences in solid water and solid butter.

BACKGROUND:

Typically as a substance is heated it expands. Because of the increase in kinetic energy supplied by the heat, the molecules of the substance speed up and move around more, increasing their volume (which decreases density). Likewise as most substances cool, they contract because their molecules slow down as their kinetic energy decreases. As they slow down their volume decreases because they take up less space (increasing density). Remember from Experiment 2.2 that less dense substance will float in more dense substances. In this experiment you will investigate if this phenomenon happens for both butter and water.

MATERIALS:

• Stick of butter or margarine (It must be fresh from the refrigerator so that it is solid)
• Two beakers or microwave-safe glass bowls
• Water
• Ice cube
• Microwave (A saucepan and stove can be substituted for the microwave.)
• Knife (A serrated one works best. You will use it to cut the butter.)
• Spoon
• Eye protection such as goggles or safety glasses

QUESTIONS:

What happens when solid butter is placed in liquid butter? What happens when solid water is placed in liquid water?

HYPOTHESIS:

Predict what will happen when solid water and butter are placed in liquid water and butter respectively.

PROCEDURE:

1. Look at the tablespoon markings on the wrapper that covers the stick of butter. Using those markings as a guide, cut ½ tablespoon off the end of the stick with the knife so that you have a small square of butter.
2. Unwrap both the piece you cut off and the rest of the stick.
3. Put the ½ tablespoon of butter back in the refrigerator until it is needed in step 8.
4. Put the rest of the stick of butter into the beaker or microwave-safe glass bowl.
5. Melt the butter in the microwave for about 1 minute. (Check after 30 seconds to see if it is melted.) You can also melt the butter in a saucepan on the stove.
6. When the butter is completely melted, take it out of the microwave. If using the saucepan, carefully pour the melted butter into the beaker or glass bowl. You now have a beaker of liquid butter.
7. Fill the other beaker with water. Set both beakers side by side.
8. Go to the refrigerator and get the solid butter you put there. Also get an ice cube from the freezer.
9. Drop the ice cube in the water.
10. Drop the ½ tablespoon of solid butter in the liquid butter.
11. Record your observations of what happened to the ice cube and the solid square of butter in your data table.
12. Clean up and put everything away.

DATA TABLE:

CONCLUSION:

What was the difference in what happened to the ice cube and the solid butter square? Explain what happened (use density in your explanation) and make connections to the text (discuss hydrogen bonding).

SUBMIT YOUR WORK