Science Assessment

Heat packs are commonly used by skiers as hand warmers. A heat pack is a pouch that contains powdered iron. When a skier takes the heat pack out of the package, oxygen from the air can enter the heat pack. Once inside the heat pack, the oxygen reacts with the iron to form iron oxide (rust), and the heat pack gets warmer.

After the chemical reaction takes place inside the heat pack, does the heat pack have more, less, or the same amount of chemical energy as before the reaction? Why?

1. The heat pack has more chemical energy after the reaction because the heat pack feels warmer.
2. The heat pack has less chemical energy after the reaction because some of its energy was transferred to the skier’s hands.
3. The heat pack has the same amount of chemical energy after the reaction. Even though the skier’s hands feel warmer, that does not change the amount of chemical energy the heat pack has.
4. The heat pack has the same amount of chemical energy after the reaction. The skier’s hands feel warmer because coldness was transferred from the skier’s hands to the heat pack.