Freezing Point Depression
Purpose: The purpose of this experiment is to determine the freezing point depression of ice by making ice cream.
Safety Precaution:
Allergy precaution! Do not touch or eat if allergic to dairy or lactose intolerant.
Materials:
• ½ cup of milk
• ½ cup of whipping cream/ heavy cream
• ¼ cup sugar
• ¼ teaspoon vanilla or vanilla flavoring
• ½ to ¾ cup of sodium chloride
• 2 cups of ice
• 1- quart Ziploc bag
• 1- gallon Ziploc bag
• Measuring cups
• Spoons
• Cups
Procedure:
1. Add the milk, whipping cream/ heavy cream, sugar and vanilla/ flavoring to the quart sized Ziploc bag. Seal the bag completely.
2. Put 2 cups of ice into the gallon Ziploc bag.
3. Add the salt to the bag of ice.
4. Place the closed quart
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Continue to rock the bag for 10-15 minutes or until the contents of the quart bag have solidified into ice cream.
7. Open the gallon bag.
8. Remove the quart bag, open it and place the ice cream into cups with spoons and eat it.
Explanation of the Science Behind this Experiment: This experiment is an example of freezing point depression. Ice melts when it absorbs energy so it can change from a solid to a liquid. On the contrary, when salt is added to the ice, it lowers the freezing point of the ice. That means that in order for the ice to melt, it needs to absorb even more energy. Once salt is added to the ice, it makes the ice colder, allowing it to freeze. Additionally, large crystals of salt are used because it takes more time for larger pieces of salt to dissolve in the water, which allows the ice cream to cool even more. In this experiment, the way to see and determine the freezing point depression is by measuring the temperature of the ice in the gallon bag before salt is added and to measure the temperature of the ice and salt once the ice cream is formed in the quart bag. By having these two measurements of temperature before and after the salt was added, shows the freezing point depression and how it works once salt is added to the