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

Background Information:
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.  What happens if you sprinkle salt on ice?

Materials:

1. 1/2 cup milk 
2. 1/2 cup whipping cream (heavy cream)
3. 1/4 cup sugar
4. 1/4 teaspoon vanilla or vanilla flavoring (vanillin) 
5. 3/4 cup sodium chloride (NaCl) as table salt or rock salt
6. 2 cups of ice 
7. 1-quart Ziploc bag 
8. 1-gallon Ziploc bag 
9. Thermometer 
10. Measuring cups and spoons 
11. Cups and spoons for eating your treat! 

Procedure:

1. Add 1/4 cup sugar, 1/2 cup milk, 1/2 cup whipping cream, and 1/4 teaspoon vanilla to the quart Ziploc bag.
2. Put 2 cups of ice into the gallon Ziploc bag.
3. Use the thermometer to measure and record the temperature of the use 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 in the gallon bag of ice and salt. Seal the gallon aug 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 col 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!

Here is a video for a clearer procedure:
https://www.youtube.com/watch?v=FmavyOIQIz0

Data:
1) What kind of ice cream are you making?
Me and my partner are doing chocolate flavored ice cream.
2) Document the temperature of the ice in the gallon bag before adding the salt.
The temperature of the ice in the gallon bag before adding the salt is 0°C.
3) Document the temperature of the ice/salt mixture in the gallon bag when the ice cream mixture begins to solidify.
The temperature of the ice/salt mixture in the gallon bag when the ice cream mixture begins to solidify is -7°C.
4) What is the temperature difference before adding the salt and after mixing for five minutes?
The temperature difference before adding the salt and after mixing for five minutes is -7°C.
5) What is the temperature difference before adding the salt and after mixing for ten minutes? 

The temperature difference before adding the salt and after mixing for ten minutes is -8°C.

Shaking the bag 

Opening the bag to check the consistency of the ice cream

Taking the temperature of the ice with the salt 

Conclusion: 
1.) What kind of chemical reaction is the process of ice cream making, as done in our lab? Explain why.
The chemical reaction that is taking place in the process of ice cream making is 

2.) Explain why salt water is harder to freeze than plain water. 
Salt water is harder to freeze than plain water because salt has a higher freezing point than water, so when its dissolved in water, its harder for it to freeze. 

3.) Is the process of making ice cream a physical or chemical change? Explain your answer.
The process of making ice cream is a physical change because of the simple fact that you can get the mixture back to its original state by letting it melt. 

4.) Why is salt used with the ice instead of sugar?
The salt is used in the ice instead of sugar because the salt makes the ice melt. Salt decreases the freezing point of water.