Heat Changes Associated with Chemical Reactions, Hess’ Law, and Reaction Profiles

Have you ever witnessed how fast race cars can travel around a track? Watching the cars on television, you may not think the cars are traveling at a great rate of speed, but when you view them at the track, they really move. When gasoline is burned in a car engine, the chemical energy is released and used to do work. The burning of gasoline produces energy and heat. Also, the fuel in the engine undergoes a transformation. By studying thermochemistry, chemists gain an understanding of the energy and heat associated with chemical reactions and physical transformations. These same chemists can even learn how to make the race cars go faster and travel for longer periods of time without refueling. In this topic, you will investigate the heat changes associated with chemical reactions.

Essential Questions

• How is heat energy transferred?
• What is the relationship between enthalpy and Hess's Law?