Put aside that store bought ice cream for this experiment. Instead, make your own tasty treat and learn some physics as well!
Image Credit: annamatic3000 via flickr
What You Need
- 1 cup of milk
- 1/4 cup of sugar
- 1 teaspoon of vanilla flavoring
- 1/2 cup of rock salt
- 4 cups of ice
- 1-quart plastic bag
- 1-gallon plastic bag
- Measuring cups and spoons
- Cups and spoons to enjoy your creation
What to Do
1. Pour 1 cup milk into a 1-quart plastic bag.
2. Add 1 teaspoon of vanilla flavoring.
3. Add ¼ cup of sugar.
4. Seal 1-quart bag tightly. If necessary double bag inside another 1-quart bag so the liquid does not leak.
5. Gently shake the bag to mix all of the ingredients together.
6. Pour 4 cups of ice into the 1-gallon bag.
7. Add ½ cup of rock salt to the 1-gallon bag.
8. Place the 1-quart bag into the 1-gallon bag and seal the 1-gallon bag tightly.
9. Gently shake or rock the 1-gallon bag for 10-15 minutes.
10. Open bags and remove the 1-quart bag.
11. Check to see if it is thick, like ice cream.
12. Pour the ice cream into a cup or bowl. Enjoy!
Ice Cream Quiz
1. What state of matter was the milk, sugar, vanilla mixture when you began?
2. What state of matter was it when you finished?
3. Why did you add the salt to the ice?
What's Going On?
When you begin, the milk, vanilla, and sugar is a liquid mixture. By the end of the activity the mixture will be solid — a freezing phase change.
The salt is added to the ice to lower the freezing point of the water. To freeze the ice cream the temperature needs to be lower below 32◦ F. When you add salt, the temperature will decrease to about 0◦ F. The ice will melt quickly as you shake your bag and the ice cream will freeze.
You may have heard of the roads being salted if it snows or when the roads are icy. Think about what we did to the ice by adding the salt. Why are the roads salted in the winter? How does this help drivers?