Energy Changes in Chemical & Nuclear Systems Learning Goals:  I will be able to explain the difference between exothermic and endothermic reaction.  I will be able to explain the difference between fission and fusion.  I will be able to explain the energy changes associated with physical/chemical/nuclear changes.

Key Terms Thermochemistry: Energy Heat Law of Conservation of Energy Temperature Thermal Energy Potential Energy Kinetic Energy Open System Closed System Isolated System Endothermic Exothermic Surroundings

What is Thermochemistry? The study of energy changes that accompany physical or chemical changes in matterThe study of energy changes that accompany physical or chemical changes in matter All thermodynamics depends on the LAW OF CONSERVATION OF ENERGYAll thermodynamics depends on the LAW OF CONSERVATION OF ENERGY Changes that occur in matter may be classified as physical, chemical or nuclearChanges that occur in matter may be classified as physical, chemical or nuclear Simpsons & thermodynamics (video)video

Law of Conservation of Energy Energy cannot be created or destroyed…but it can change forms (see the pic) and often it is ‘LOST’…as heat the total energy of a system and its surroundings remains the samethe total energy of a system and its surroundings remains the same

Thermodynamics

Exothermic vs. Endothermic Exothermic – energy (heat - q) is released to the environment Feels HOT! Endothermic – energy (think heat) is absorbed from the environment. Feels COLD! DEMOS

Nuclear Energy - Fusion Large, heavy nuclei are formed when small atomic massed atoms combine. Eg. THE SUN!!

Nuclear Energy - Fission When smaller nuclei are formed as a result of the splitting of heavier atomic masses. Eg. NUCLEAR REACTORS!