Ice Cream Lab (this is a good lab to do during chapter 6, 14 or 15 if you miss a lab in class)

(35 points)

Purpose: (4 points)    To observe the physical changes of ice cream ingredients using NaCl to lower the melting/freezing point of ice/water.

 

Materials: (4 points)           Sugar                          Large plastic bag

                                            Milk                             Paper Bowls to eat out of

                                            Half and half                 Ice

                                            Cream                          Salt (rock salt)

                                            Vanilla                         Small cup/spoon     

 

Procedure:            1.  Combine the following materials in the plastic bag:

a.       ½ cup (120 ml) of milk.

b.      ½ cup (120 ml) of half and half.

c.       1 cup (236 ml) of whipping cream.

d.      ½ cup (120 ml) sugar.

e.       ½ tablespoon (10 ml) vanilla.

 

2.      Seal bag and gently mix the contents in the bag.

3.      Record observations of what the contents look like at 0.0 minutes.

4.      Place a layer of crushed ice in the blue bin, so that it covers the bottom.

5.      Sprinkle a layer of salt onto the ice.

6.      Place your sealed bag of ice cream mix in the center of your bin (on the ice).

7.      Continue adding layers of ice and salt until it is near the top of the bin.

8.      Shake for 30 minutes.

9.      After 30 minutes, check your bag; if it’s hard eat it. If it’s still soft continue shaking. 

10.  Record observations.  If necessary, add more ice/salt to the bin. 

11.  Shake for 20 more minutes.

12.  Check your bag.  Record observations.

13.  Open it up and…enjoy!

 

 

Data:           

Observations: (15 points) At 0.0, 30.0 and 50.0 minutes write an observation when the questions below apply.  Each observation should answer the following questions:

 

·        How molecules behave in a solid.

  • How molecules behave in a liquid.
  • What’s its Viscosity?

·        Is it a Mixture or a Solution?

  • Where is the thermal energy of the ingredients being transferred?
  • Is it Crystalline or an Amorphous Solid.
  • Describe the movement of Molecules.
  • Characteristic properties of salt and water.

                       

 

Time

Observations: answering the above questions

0.0 minutes

 

 

30.0 minutes

 

 

50 minutes only

 if your ice

cream is still soft

 

 

 

Conclusion: (12 points)

 

1.  Explain the physical changes that take place during this process.

2.      The term thermodynamics = the transfer of heat.

Think about the thermodynamics of making ice cream… that is… think about the transfer of heat between substances:  ice, salt, ice cream mix, environment. 

a.      Explain the thermodynamics of melting ice (while making ice cream).

b.      Explain why the ice cream mix freezes… in terms of the transfer/flow of heat.

 

3.      Adding salt lowers the melting point of the ice.

Explain why this is advantageous when making ice cream.

4.      Is making ice cream a physical or chemical reaction?  Explain your choice.