Wednesday, April 21, 2010

I propose we make ice cream in a bag!


IProposeWe MAKE ICE CREAM IN A BAG!
Links:
How to make ice cream in a bag
How does the ice cream freeze without a freezer?




Materials:
  • 1/2 cup milk
  • 1/2 cup whipping cream (heavy cream)
  • 1/4 cup sugar
  • 1/4 teaspoon vanilla or vanilla flavoring
  • 1/2 to 3/4 cup sodium chloride (NaCl) as table salt or rock salt
  • 2 cups ice
  • 1-quart ZiplocTM bag
  • 1-gallon ZiplocTM bag
  • themometer
Procedures:
  1. Add 1/4 cup sugar, 1/2 cup milk, 1/2 cup whipping cream, and 1/4 teaspoon vanilla to the quart ziplocTM bag. Seal the bag securely.
  2. Put 2 cups of ice into the gallon ziplocTM bag.
  3. Use a thermometer to measure and record the temperature of the ice in the gallon bag.
  4. Add 1/2 to 3/4 cup salt (sodium chloride) to the bag of ice.
  5. Place the sealed quart bag inside the gallon bag of ice and salt. Seal the gallon bag securely.
  6. Gently rock the gallon bag from side to side. It's best to hold it by the top seal or to have gloves or a cloth between the bag and your hands because the bag will be cold enough to damage your skin.
  7. Continue to rock the bag for 10-15 minutes or until the contents of the quart bag have solidified into ice cream.
  8. Open the gallon bag and use the thermometer to measure and record the temperature of the ice/salt mixture.
  9. Remove the quart bag, open it, serve the contents into cups with spoons and ENJOY!


Safety Precautions:
  • Make sure that there aren't any sharp objects near the bag of ice and milk. If there is, the bag can easily be tampered with and a hole could be made.
  • Make sure to put the milk and whipping cream in the refrigerator so the milk and whipping cream will not spoil.


Scientific Principles:
  • Salt mixed with ice in this case also causes the ice to melt. When salt comes into contact with ice, the freezing point of the ice is lowered. Water will normally freeze at 32 degrees Farenheit. By lowering the temperature at which ice is frozen, we are able to create an environment in which the milk mixture can freeze at a temperature below 32 degrees Farenheit into ice cream.

Objectives:
  • Investigate the effects of temperature change on phase changes;
  • Investigate the effects of changes in freezing point;
  • Utilize these concepts in making ice cream.