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 matter

• All thermodynamics depends on the LAW OF CONSERVATION OF ENERGY

• Changes that occur in matter may be classified as physical, chemical or nuclear• Simpsons & thermodynamics (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 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!