1. Endothermic vs Exothermic Reactions
Mrs. Chan

2. Energy
Energy is the capacity to do some kind of work, such as moving an object, forming a new compound, or generating light.
Energy is always involved when there is a change in matter.

3. System and Surroundings
The universe is divided into two parts:
The SYSTEM is the part of the universe on which to focus attention.
The SURROUNDINGS includes everything else in the universe.

4. All physical and chemical changes involve a change in energy.
Every Change in Matter Involves a Change in Energy
All physical and chemical changes involve a change in energy.
Some involve releasing energy, some involve absorbing energy.

5. Endothermic Processes
Any change in matter in which energy is absorbed from the surroundings to the system is an endothermic process.

6. Endothermic Process Examples
Physical Changes
Chemical Changes
The melting of ice
The boiling of water
The reaction between barium hydroxide and ammonium nitrate

7. Exothermic Processes
Any change in matter in which energy is released from the system to the surrounding is an exothermic process.

8. Exothermic Process Examples
Physical Changes
Chemical Changes
The freezing of water
The condensation of water
The explosive reaction between hydrogen and oxygen to form water

10. The Law of Conservation of Energy
Energy can be absorbed by the surroundings or released to the surroundings, but it cannot be created or destroyed.
The law of conservation of energy states that during any physical or chemical change, the total quantity of energy remains constant.

11. Conservation of Energy in a Chemical Reaction

12. Temperature vs Heat
Temperature – Measure of the random motions (average kinetic energy) of the components of a substance. Heat – Flow of energy due to a temperature difference.