Hot and cold packs use chemical reactions to produce heating or cooling effects. Heat packs contain sodium acetate that undergoes an exothermic reaction when mixed with water, releasing heat. Cold packs contain ammonium nitrate that reacts endothermically with water, absorbing heat from its surroundings. These chemical reactions allow the packs to be used therapeutically by providing hot or cold temperature changes.

1. BY: Jack Hudgins

2. Hot and cold packs are a product of a chemical
reaction between a supersaturated solution of
Sodium Acetate and water in Heat packs and
Ammonium Nitrate and water in cold packs. The
reason these work is that the reaction either causes
heat to be expelled or absorbed in the reaction.

3. http://www.youtube.com/watch?v=6tIfFJlP85I Heat packs

4. NH 4 NO3 (s) → NH4
+ (aq) + NO3
- (aq) is the reaction inside cold packs
http://sites.jmu.edu/chemdemo/2011/06/08/amonium-nitrate-reaction/
 This is ammonium nitrate

5. The supersaturated solution releases the energy
that caused it to become a supersaturated
solution when the solution is thrown out of the
balance that it is in. Although it is in balance, it is
a very unstable balance and can easily be
crystalized. This process is a exothermic reaction
because energy in the form of heat is released.

6. The chemical reaction of ammonium nitrate and
water causes the ammonium nitrate to absorbs
extreme amounts of heat. This in turn gives us the
cold we get in the pack which helps will swelling.
Because it absorbs energy in the form of heat, it is an
endothermic reaction.

7. One example of the type of ice packs sports players use.

8.  http://en.wikipedia.org/wiki/Ice_pack
 http://www.helium.com/items/1362483-the-chemistry-of-reusable-
heat-packs
 http://www.pa.msu.edu/sciencet/ask_st/031595.html