Name____________________________ Date_________ Pd._____
We All Scream for Ice Cream
A freezing mixture has three components: ice, salt, and brine. Brine is a result of salt dissolving on ice creating a solution. Freezing does not take place until the brine forms and gets cold enough to lower the temperature of the mixture to it's freezing point. As the ice melts, it absorbs heat from the brine and so lowers it's temperature. Salt as it dissolves, maintains the concentration of the brine. As the ice absorbs more and more heat from the brine the resultant reaction is a lowering of temperature. As this reaction is happening, it is also absorbing heat from the cream mixture which is in the can. This combination of events allows the desired mixture, the cream, to form ice crystals and freeze. That is how ice cream is made.
Ingredients:
2 cups Whole milk
1/2 cup sugar
1 1/2 tsp. vanilla extract
1/8 tsp. salt
various flavoring agents
Directions:
1. Measure milk, sugar, vanilla, and salt into cream can.
2. Mix well to dissolve sugar.
3. Assemble ice cream maker and add ice and salt.
Observation and Data:
Answer the following questions, while conducting the lab:
1. What is the temperature of plain ice water? Fahrenheit and Celsius.
2. Approximately how long did it take for the milk mixture to start forming crystals?
3. As the milk started to freeze, crystals began to form. What do you
suppose those crystals are made of?
4. After the ice cream is done, what is the temperature of the brine?
5. If water freezes at 32 degrees F, and the temperature of the brine is so cold, Why
doesn't the brine mixture freeze entirely?
6. Stirring the milk mixture as it freezes is an important step in making
ice cream. Why do you think stirring is important?
7. Calculate the conversion of the following: Show calculations
a. 32 degrees F = ___________ degrees C
b. 20 degrees C = ___________ degrees F
c. 212 degrees F = ___________ degrees C
d. 28 degrees C = ___________ degrees F
Formulas: F = 9/5 C + 32 C = 5/9( F - 32)