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Making Ice Cream-Rock and Roll Style Here’s a scientific recipe that you can use to make your own ice
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Making Ice Cream-Rock and Roll Style

Legend has it that the Roman emperor, Nero, is credited as the first person to make ice cream. Nero commanded slaves to bring snow down from the mountains, which was then used to freeze the flavored cream mixture. The secret was to lower the freezing point of snow in order to freeze the cream. How? The scientific secret is SALT! Here's a scientific recipe that you can use at home to make your own ice cream.

See the video

Materials

- 1 Large coffee can or plastic jar
- 2 quart size zipper-lock bag
- Half & Half Cream
- Crushed ice
- Salt (rock salt works great)
- Vanilla
- Sugar
- Towel (or winter gloves)
  1. Fill the coffee can or large plastic jar half full with crushed ice.
  2. Add about 6 tablespoons of salt to the ice. Seal the container and mix for a few minutes by rolling the container back and forth on the floor. Hey, you might even have to wear gloves! Why? Measure the temperature of the mixture with a thermometer. The salt and ice mixture gets down to about 14 degrees F (-10 degrees C)!
  3. Use the quart size zipper-lock bag to mix the following ingredients:
    • 1/2 cup of half & half cream
    • 1 tablespoon sugar
    • 1/2 teaspoon vanilla extract
  4. Seal tightly, allowing as little air to remain in the bag as possible. Too much air left inside may force the bag open during shaking.
  5. Place the bag inside the coffee can with the ice mixture and seal and place the lid on tightly. Here comes the fun part... find someone who will roll the can back and forth on the floor with you. Only the people who help get to enjoy the ice cream! Roll it everywhere... on the floor, over the bed, under the table, on top of Uncle Bill... just keep rolling it. Five to eight minutes is adequate time for the mixture to freeze into ice cream. You might need to check on your ice cream concoction after 5 minutes to see if it's frozen. If not, keep rolling.
  6. Remove the bag from the can and rinse it well with water. You don’t want any salt water accidentally getting into your ice cream.
  7. Use your spoon to eat the ice cream right out of the bag!

How does it work?

What does the salt do? Just like we use salt on icy roads in the winter, 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.

The lowering of the freezing point depends on the amount of salt added. The more salt added, the lower the temperature will be before the salt- water solution freezes. For example, water will normally freeze at 32 degrees F. A 10% salt solution freezes at 20 degrees F, and a 20% solution freezes at 2 degrees F.

When salt is added to the ice, some of the ice melts because the freezing point is lowered. Always remember that heat must be absorbed by the ice for it to melt. The heat that causes the melting comes from the surroundings (the warmer cream mixture). By lowering the temperature at which ice is frozen, you were able to create an environment in which the cream mixture could freeze at a temperature below 32 degrees F into ice cream.

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