How to Make Home Made

                                    Vanilla Ice Cream

Background: What happens if you sprinkle salt on ice? It melts the ice because it changes the point at which a substance freezes. Certain substances affect the state of ice. When salt is sprinkled on ice, for example, it causes the ice to melt. This chemical reaction is actually a heat energy transfer. Water freezes at 0°C. a saturated saltwater solution freezes at -32°C.

Objectives: To develop observation skills, understand the scientific process through active experimentation and comparison, and understand that chemicals can change the properties of water. 

Materials:
*1/2 cup milk
*1/2 cup whipping cream (heavy cream)
*1/4 cup sugar
*1/4 teaspoon vanilla or vanilla flavoring (vanillin)
*3/4 cup sodium chloride (NaCl) as table salt or rock salt 
*2 cups of ice
*1-quart Ziploc bag
*1-gallon Ziploc bag 
*Themometer
*Measuring cups and spoons
*Cups and spoons for eating your treat!

Procedures:
1.) Add 1/4 cup of sugar, 1/2 cup milk, 1/2 cup of whipping cream, and 1/4 teaspoon vanilla to the quart Ziploc bag. Be sure to seal the bag correctly.

2.) Put 2 cups of ice into the gallon Ziploc bag.

3.) Use the 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. Then seal the gallon bag carefully until completely sealed.

6.) Gently rock the gallon bag from side to side. It's best to hold the bag from 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, grab your spoons and ENJOY!


Data:
1.) What kind of ice cream are you making?
- Vanilla

2.) Document the temperature of the ice in the gallon bag before adding salt. 
- 0°C

3.) Document the temperature of the ice/salt mixture in the gallon bag when the ice cream mixture begins to solidify. 
- 9°C

4.) What is the temperature difference before adding he salt and after mixing for 5 minutes?
- 7°C (before it was 0°C and after it was -8°C)

5.) What is the temperature difference before adding he salt and after mixing for 10 minutes?
- 8°C (before it was 0°C and after it was -9°C)

Conclusion:

1.) What kind of chemical reaction is the process of ice cream making, as done in our lab? Explain why.

2.) Explain why salt water is harder to freeze than plain water.
- When combining salt with ice it causes the freezing point to decrease. when that occurs, the ice becomes colder than before the mixture making the ice cream freeze.
 

3.) Is the process of making ice cream a physical or chemical change? Explain your answer.
 - making ice cream is a chemical change because you are unable to turn the ice cream back into your beginning substances.

4.) Why is salt used with the ice instead of sugar?
- sugar doesn't dissolve well in water. when a compound breaks down when dissolving, like salt, it lowers the freezing point more than compounds that don't break down. 

 

  Resources:

http://chemistry.about.com/cs/howtos/a/aa020404a.htm

Making home made ice cream video:  https://www.youtube.com/watch?v=7TiMhu7nDdU