1. Thermochemistry
Chapter 10

2. Energy-ability to do work or produce heat Ex: Cars need energy to run.
People need energy to live.

3. Energy Classifications
Potential energy-energy due to position or composition
Kinetic energy-energy due to motion

4. Measuring Energy Changes
calorie(c)-amount of energy required to raise the temperature of one gram of water by one Celsius degree. (Food you eat is measured in Kilocalories which is abbreviated C).
Joule (J)-the SI unit of energy
1 c=4.184J

5. 1st Law of Thermodynamics
The law of conservation of energy states that energy cannot be created or destroyed. Therefore, the total energy in a system is conserved.

6. What’s the difference between energy and heat?

7. Temperature-measures the molecular motions of the particles
Heat(Enthalpy)-the flow of energy due to temperature difference
**You can have temperature without having heat

8. Exothermic reactions-energy flows out of the system.
Endothermic reactions-energy flows into a system.
q or H represents heat

9. Label as exo or endo Your hand gets cold when you touch ice.
Ice cream melts.
Propane is burning in a propane torch.
Water drops on your skin evaporate after swimming.

10. Answers Exo hand+icewater+heat
(your hand feels cold because heat is leaving, your hand has less energy after it touches the ice)
2) endo
Ice cream+heat  melted ice cream
(the melted ice cream has more energy so heat must have been added to the system)

11. 3) exo- propane gas  heat
(heat is released)
4) endo
water+body heatevaporation
(in order for something to evaporate heat has to be added)

12. Hess’s Law
Hess’s Law-the overall enthalpy change in a reaction is equal to the sum of enthalpy changes for the individual steps in the process

13. Entropy
Entropy-a measure of the disorder or randomness
Abbreviated with ∆S
If you take a deck of cards and drop them on the floor, that would have high entropy.
If you buy a new deck, that would have low entropy.

14. 2nd Law of Thermodynamics
The entropy of the universe is always increasing
Processes in nature are driven toward lowest enthalpy and highest entropy