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

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

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

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

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

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

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

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