1. CHEMISTRY Unit 11 Notes: Intro to Fire & Energy

2. (1) What Is Energy?
A measure of the work involved in moving or changing something.
NOT a substance. NOT matter.
Chemists measure:
How much energy moves in and out of a system.
The different forms energy converts to.

3. (2) Changing Matter & Energy
To change matter you MUST change energy.
Reactions can:
Use/absorb energy
Release energy

4. (3) Combustion Requires Oxygen gas (O2).
Requires a fuel  A fuel is anything made of hydrocarbons.
Products of Combustion:
Carbon Dioxide
Water
Hot Gases (sometimes emitting light)
Heat Transfer
Sometimes explosions

7. CHEMISTRY Unit 11 Notes: Endothermic vs. Exothermic Reactions

8. (1) Chemical Reactions & Energy
Chemical Reactions Involve:
Changing of matter
Transfer of energy
Energy Can Be Transferred 2 Ways:
Exothermically
Endothermically

9. (2) Heat, System & Surroundings
Heat  The transfer of energy between two substances due to a difference in energy.
“Hot” = More / Gain Heat Energy
“Cold” = Less / Loss of Heat Energy
System  The process being focused on.
Surroundings  Everything outside the “system”.

11. (3) Exo & Endothermic Reactions
Exothermic Reactions 
Release energy.
Will feel “hotter”.
Energy goes from System to Surroundings.
Endothermic Reactions 
Gain or Take in energy.
Will feel “cooler”.
Energy goes from Surroundings to System.

12. --Exothermic Reactions--

13. --Endothermic Reactions--

14. CHEMISTRY Unit 11 Notes: Thermodynamics

15. (1) 1st Law of Thermodynamics
Energy is conserved when transferred.

17. (2) 2nd Law of Thermodynamics
Thermal energy transfers from the hotter object, to the cooler object.
Some energy is always lost to the surrounding.
Energy transfer will continue until both objects are in energy equilibrium.

20. (3) Thermal Equilibrium
When 2 objects in contact with one another reach the same temperature.