Ice Cream Lab

Haley Heptig
May 2, 2014
Chemistry
H18
Period 5

Background Info:
   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 degrees Celsius. A saturated saltwater solution freezes at -32 degrees Celsius.

What happens if you sprinkle salt on ice?
- The ice begins to belt.


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

Materials:
-1/2 cup of milk
-1/2 cup of whipping cream (heavy cream)
-1/4 cup of sugar
-1/4 teaspoon of vanilla or vanilla flavoring (vanillin)
-3/4 cup of 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!

Video:







Procedure:
1.) Add 1/4 cup of sugar, 1/2 cup of milk, 1/2 cup of whipping cream (heavy cream), and 1/4 teaspoon vanilla to the quart Ziploc bag. Seal the bag securely.

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

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

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

3.) Document the temperature of the ice/salt mixture (not the ice cream) in the gallon bag when the ice cream mixture begins to solidify.* DO NOT PUT THE THERMOMETER IN THE ICE CREAM BAG.
- 5 degrees Celsius.

4.)What is the temperature difference before adding the salt and mixing for 5 minutes?
- -6 degrees Celsius.

5.) What is the temperature difference before adding the salt and after mixing for 10 minutes?
- -3 degrees Celsius.

 
* Deja and I making homemade ice cream.

Post-Lab Questions:
1.) What kind of chemical reaction is the process of ice cream making, as done in our lab? Explain why.
- This an endothermic reaction. Energy has to be absorbed from the temperature of the environment outside the bag, which helps the ice cool the ice cream, along with the salt added to the ice.

2.) Explain why salt water is harder to freeze than plain water.

- This is because salt water has a lower freezing point than plain water. Plain water freezes at 0 degrees Celsius while salt water freezes at -32 degrees Celsius.

3.) Is the process of making ice cream a physical or chemical change? Explain your answer.

- This is a physical change because the ice cream changes from a liquid state to a solid state. There is nothing about the compounds of the ice cream that chemically changes.

4.) Why is salt used with the ice instead of sugar?

- Sugar does not dissolve in water as well as salt does.

Work Cited:
http://www.sci-experiments.com/ice_cream/saltwater.html

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

http://www.kentchemistry.com/links/Matter/PhysicalChemicalChanges.htm

http://scienceofeverydaylife.discoveryeducation.com/families/pdfs/activities/Kitchen-Chemistry.pdf

http://www.benjerry.com.sg/flavors/from-cow-to-cone;jsessionid=1D0A1408E2327D52ADD41A999D8C2B7B