1. Clicker #1 Which is lower in potential energy and more stable?
unburned match or burned match
A) unburned match
B) burned match

2. Exothermic: more energy leaves the system overall
Endothermic: more energy goes into the system overall
2H2 + O2  2H2O
2H2O  2H2 + O2

3. Example #1
Is the freezing of water an endothermic or exothermic process? (The system is underlined.)
Exothermic

4. Clicker #2
Is the boiling of water an endothermic or exothermic process? (The system is underlined.)
A) endothermic
B) exothermic

5. Example #2
Is an activated cold pack an endothermic or exothermic process? (The system is underlined.)
Endothermic

6. Clicker #3
Is an activated hot pack an endothermic or exothermic process? (The system is underlined.)
A) endothermic
B) exothermic

7. Clicker #4
Is a racquetball frozen by liquid nitrogen an endothermic or exothermic process? (The system is underlined.)
A) endothermic
B) exothermic

8. Example #3
Is the thermite reaction (the chemical reaction) an endothermic or exothermic process? (The system is underlined.)
Exothermic