Shakira Cruz May 2, 2014
H-23 Chemistry
ICE CREAM LAB
BACKGROUND:
BACKGROUND:
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 zero degree Celsius ( PUT IN NUMBERS ). A saturated salt water solution freezes at -32 ( Degrees Celsius ). What happens if you sprinkle salt on ice ?
Answer : If you sprinkle salt on ice , the ice will melt due to the changes of the point at which your substance freezes.
Objectives :
To develop observation skills, understand the scientific process through active experimentation and comparison, and understand that chemicals can change the properties of water.
Material's :
* 1/2 cup milk
* 1/2 cup whipping cream ( heavy cream)
* 1/4 cup sugar
* 1/4 teaspoon vanilla flavoring ( vanillin )
* 3/4 cup sodium chloride ( NaCl ) as a table salt or rock salt
* 2 cups of ice
* 1- quart Ziploc bag
* 1- gallon Ziploc bag
* A thermometer
* Measuring cups and spoons
* Cups and spoons for eating your treat
Procedure:
VIDEO LINK: https://www.youtube.com/watch?v=hZRCP7wjG4U
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 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. Its best to hold it by the top seal or use gloves between the bag and your hands because the bag will be cold and can damage your skin.
7. Continue to rock the bag for 10 to 15 minutes or until the contents of the quart bag have solidified into ice cream.
8. Open the gallon bag and 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.
-10° C
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.
1° C
4. What is the temperature difference before adding the salt and after mixing for 5 minutes?
11° C
5. What is the temperature difference before adding the salt and after mixing for 10 minutes?
-10° C
Conclusion Questions:
1. What kind of chemical reaction is the process of ice cream making, as done in our lab ? Explain why.
- The process of making ice cream is an endothermic reaction because the reaction gives off heat to melt the ice that was placed inside of the bag.
2. Explain why salt water is harder to freeze than plain water ?
- Salt water is more harder to freeze than plain water because salt water has a lower freezing point than fresh plain water.
3. Is the process of making ice cream a physical or chemical change? Explain your answer.
- Making ice cream is most likely to be a physical change. The reason why is because it involves changing the viscosity and lowering the temperature to keep the ice cream cold and cool threw the process.
4. Why is salt used in the ice instead of sugar ?
- Salt is used in ice to lower the melting temperature of the ice down to at least 0F. So that the coldness of the salt that was used in the ice could quickly and easily freeze the Ice cream.
Sources:
http://www.madsci.org/posts/archives/1998-03/890115623.Ch.r.html
http://science.howstuffworks.com/nature/climate-weather/atmospheric/road-salt.htm
* 3/4 cup sodium chloride ( NaCl ) as a table salt or rock salt
* 2 cups of ice
* 1- quart Ziploc bag
* 1- gallon Ziploc bag
* A thermometer
* Measuring cups and spoons
* Cups and spoons for eating your treat
Procedure:
VIDEO LINK: https://www.youtube.com/watch?v=hZRCP7wjG4U
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 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. Its best to hold it by the top seal or use gloves between the bag and your hands because the bag will be cold and can damage your skin.
7. Continue to rock the bag for 10 to 15 minutes or until the contents of the quart bag have solidified into ice cream.
8. Open the gallon bag and 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.
-10° C
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.
1° C
4. What is the temperature difference before adding the salt and after mixing for 5 minutes?
11° C
5. What is the temperature difference before adding the salt and after mixing for 10 minutes?
-10° C
Conclusion Questions:
1. What kind of chemical reaction is the process of ice cream making, as done in our lab ? Explain why.
- The process of making ice cream is an endothermic reaction because the reaction gives off heat to melt the ice that was placed inside of the bag.
2. Explain why salt water is harder to freeze than plain water ?
- Salt water is more harder to freeze than plain water because salt water has a lower freezing point than fresh plain water.
3. Is the process of making ice cream a physical or chemical change? Explain your answer.
- Making ice cream is most likely to be a physical change. The reason why is because it involves changing the viscosity and lowering the temperature to keep the ice cream cold and cool threw the process.
4. Why is salt used in the ice instead of sugar ?
- Salt is used in ice to lower the melting temperature of the ice down to at least 0F. So that the coldness of the salt that was used in the ice could quickly and easily freeze the Ice cream.
Sources:
http://www.madsci.org/posts/archives/1998-03/890115623.Ch.r.html
http://science.howstuffworks.com/nature/climate-weather/atmospheric/road-salt.htm
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