Looking for a fun way to beat the heat this week and learn a little about chemistry? You can make ice cream in a bag at home, and observe how the interaction of ice and salt causes the temperature of the ice to drop!

Gather these Supplies (Makes 1 serving)

Milk, Vanilla Extract, Sugar, Ice, Salt, Quart Bag, Gallon Bag, Toppings

Ice Cream Base Ingredients (in the quart bag)

1/2 cup of milk

1/4 teaspoon vanilla extract

1 tablespoon of sugar

Ice/Salt Mixture (in the gallon bag)

4 cups of ice

1/2 cup of salt

Have oven mitts, gloves or a towel so that your hands don’t get too cold.

Directions:

  1. Make the ice cream base mixture by combining the sugar, milk, and vanilla in the quart seal-able bag. Squeeze as much air out as you can and seal tight!
  1. In the gallon bag, put the ice, salt, and the quart bag containing the ice cream base mixture. Seal it tight!
  1. Put on the oven mitts or wrap the bag in the towel.
  1. Shake the bag for about 5-10 minutes, until the ice cream hardens.
  1. Carefully remove the small bag from the large bag and quickly rinse it off the zipper opening. There will be salty water on it and you don’t want to get that in your ice cream.
  1. Open the small bag, put the ice cream in a bowl, and add your favorite toppings.
  1. Enjoy!!!
  1. Clean up!!!

How did you do that? Science!

Some chemical reactions make substances colder. These are endothermic reactions.

Adding salt is the key component in this experiment. Heat flows from hot to cold. The ice is colder than the base mixture, so as heat leaves the base mixture the ice starts to melt. By adding the salt to the ice, the freezing point of the ice/salt mixture is lowered. (Remember the directions? Put on the oven mitts or wrap the bag in the towel. You need to do that to protect your hands from the cold.) Since the ice/salt mixture is now colder, even more heat leaves the base mixture. As the base mixture loses heat, it begins to freeze. The frozen water molecules in the milk are what creates the ice cream in the bag.

Do-It-Yourself Slushy

Don’t like ice cream? You can substitute juice for the ice cream base mixture and make a homemade slushy. Just add juice to the quart bag and seal it tight. Put the small juice bag into the ice/salt mixture and shake, shake, shake. After about 5 to 10 minutes, you’ll have a juice slushy! Remember to give the slushy bag a quick rinse, especially the zipper opening. Enjoy!!!

– Kris, Youth Services Specialist