1. C OLD P ACK C HEMISTRY Caroline Manion

2. P ROBLEM AND Q UESTION What happens when instant cold packs are activated? The purpose of this experiment was to discover which amount of ammonium nitrate (NH 4 NO 3 ) becomes the coldest when dissolved in 100 mL of water.

3. B ACKGROUND I NFORMATION Ammonium Nitrate (NH 4 NO 3 ) is a solid, odorless, colorless crystalline salt used in fertilizers and explosives. When combined with water, NH 4 NO 3 undergoes an endothermic reaction, absorbing the heat in the solution.

4. H YPOTHESIS If five different amounts of ammonium nitrate (10.0g, 20.0g, 30.0g, 40.0g, and 50.0g), the beaker containing the 50.0g will have the lowest average temperature after three trials.

5. M ATERIALS 5 Beakers Distilled water (100mL per beaker) Ammonium Nitrate (NH 4 NO 3 ) Temperature Probe Stirring Rod

6. P ROCEDURE 1. A beaker was filled with 100mL of distilled water. The starting temperature of the water was taken and recorded 2. 10.0g of NH 4 NO 3 were measured and added to the water. 3. The solution was stirred and the temperature taken after 30 seconds. 4. Steps 1-3 were repeated for 20.0g. 30.0g, 40.0g, and 50.0g of NH 4 NO 3. 5. Steps 1-4 were repeated for 2 more trials of each amount.

7. V ARIABLES Independent Amount of NH 4 NO 3 Dependent Temperature of water after 30 seconds Constant Amount of water Amount of time the solution sat for (30 s)

8. D ATA AveragesBeaker 1Beaker 2Beaker 3Beaker 4Beaker 5 Initial Temp. of Water 19.5° C 19.8° C21.0° C20.9° C Temp. After 30 seconds 13.4° C8.4° C5.2° C2.9° C0.5° C Beaker 1Beaker 2Beaker 3Beaker 4Beaker 5 Heat of Reaction-255-930-1800-3000-4000

9. D ATA

11. C ONCLUSION The Hypothesis was supported because beaker 5, which contained 50.0g of NH 4 NO 3 was the coldest after 30 seconds. Some sources of error were that only 3 trials were conducted due to a limited supply of NH 4 NO 3 and instances where the software to record the temperature was not started right away. Further research would include more trials and to discover at which amount of NH 4 NO 3 the heat of the reaction no longer follows a linear trend.

12. T HANK Y OU ! References Ammonium nitrate. (n.d.). Retrieved October 8, 2010, from Houghton Mifflin Company website: http://www.answers.com//nitrate Brain, M. (2006, November 29). Cold packs. In How refrigerators work. Retrieved October 17, 2010, from http://home.howstuffworks.com/.htm# Helmenstine, A. M. (n.d.). Endothermic and exothermic reactions. Retrieved October 8, 2010, from http://chemistry.about.com////a.htm New World Encyclopedia Contributors. (2008, November 1). Ammonium nitrate. In Ammonium nitrate. Retrieved October 5, 2010, from New World Encyclopedia website: http://www.newworldencyclopedia.org//_nitrate Princeton university. (2010). Heat energy. Retrieved October 21, 2010, from Princeton university website: http://wordnet.princeton.edu/ Tissue, B. M. (2000). Reaction thermodynamics. Retrieved October 8, 2010, from http://www.files.chem.vt.edu/ed//.html Unknown. (2010, January/). Balanced equation for ammonium nitrate and water [Online forum message]. Retrieved from http://www.blurtit.com/.html Weisstein, E. W. (2007). Heat capacity. Retrieved October 21, 2010, from Wolfram research website: http://scienceworld.wolfram.com//.html Whyte, D. B. (2009, June 18). Cold pack chemistry. Retrieved October 17, 2010, from http://www.sciencebuddies.org/fair-projects/_ideas/_p081.shtml Wilbraham, A. C., Staley, D. D., Matta, M. S., & Waterman, E. L. (2008). Heat of solution. In Chemistry (p. 525). Upper Saddle River, NJ: Pearson Prentice Hall.