Homemade Icecream

Introduction:
Ice cream involves a lot of chemical reactions when made.  For ice to melt, it has to absorb energy, which causes the change from ice to water (solid to liquid).  Because ice is used to cool the liquids/ingredients in ice cream, we add salt (NaCl) to lower the freezing point of the ice cream.  Now more energy has to be consumed to melt the ice.  The ice becomes cooler when it's freezing point is lowered, and thus freezes.

Materials:

• Ice cubes (enough to fill a gallon sized bag about half full)
• 1 cup of half and half 
• 1/2 Cup of salt
• 2 tablespoons sugar
• 1/2 teaspoon vanilla extract
• 1 gallon sized ziplock bag
• 1 pint sized ziplock bag

Steps: 

• Combine the sugar, half and half, and vanilla extract into the pint sized bag and seal it
• Place salt and ice in the gallon sized bag and seal 
• Shake the bag until the contents of the pint sized bag harden

Results: 

The ice cream turned out great.  However, I think that we either needed more ice or bigger salt crystals since it took forever to get it to the right consistency.  Also, gloves would have been nice since my hands were frozen afterwards.