Cold Pack Chemistry: Where Does the Heat Go?
Materials:
· Styrofoam cups 12-ounce (5)
· Water, distilled
· Graduated Cylinder 100mL
· Latex or nitrile gloves
· Safety goggles
· Instant cold packs containing ammonium nitrate and water
· Plastic bowl, disposable
· Weight boats or wax paper
· Plastic Spoons (5)
· Newspaper scrap
· Digital scale
· Digital thermometer
· Digital timer
Research:
Key Words
Exothermic-chemical reactions that produce heat.
Endothermic-reactions that are followed by the absorption of heat.
Ammonium Nitrate- a white crystalline solid used as a fertilizer and as a component of some explosives.
Ion-an atom or molecule with a net electric charge due to the loss or gain of one or more electrons
Heat energy-a form of energy that is transferred by a difference in temperature
Entropy-a thermodynamic quantity representing the unavailability of a system's thermal energy for conversion into mechanical work, often interpreted as the degree of disorder or randomness in the system.
Joules- unit for energy
Heat capacity- the number of heat units needed to raise the temperature of a body by one degree.
In cold packs there is a endothermic reaction that goes on. From the research I found out that cold pack becomes in a way ‘activated’ when the water and the ammonium nitrate in the cold pack mix. When this happens the cold packs starts to cool. This is because many cold packs contain ammonium nitrate a white crystalline solid which when dissolved with water spilt into positive ions and negative ions through this process the water cools and the cold pack in turn cools.