1. Unit: Thermochemistry
Day 1 - Notes
Unit: Thermochemistry
Heat, Temperature, Energy Conversions

2. After today you will be able to…
Explain what thermochemistry is
List different types of energy
Explain what happens to particle motion when heat energy is added
Convert between units of calories (cal), Joules (J) , and kilo-Joules (kJ)

3. Thermochemistry: The study of heat changes that occur during chemical reactions and physical changes of state.
Energy: The ability to do work or supply heat.

4. Different Forms of Energy
Kinetic
Potential
Heat
Solar
Nuclear
Wind
Sound
Magnetic

5. Heat: (q) a form of energy
Flows from warmer objects to cooler objects
If two objects come into contact with one another, heat will move from the warmer object to the cooler object until they are the same temperature.
-At this point, equilibrium is reached.

6. When you add heat energy, molecules move faster; temperature increases.
Temperature: a measure of heat, increase heat, increase temperature
Chemical Potential Energy: stored energy in chemical bonds
Depends on the type of atoms and arrangement

7. In a chemical reaction, either:
PE is converted to heat (heat is given off – feels hot, exothermic)
Heat is absorbed and converted to PE (feels cool, endothermic)

8. calorie (cal): chemistry calorie! Calorie (Cal): food calorie
Law of Conservation of Energy: Energy can neither be created nor destroyed, only converted from one form to another.
Units of Energy:
Joule (J)
calorie (cal): chemistry calorie!
Calorie (Cal): food calorie
- 1 food Cal = 1000 chemistry cal
- 1 cal = 4.184J

9. Conversions between energy units:
Example: How many calories are in 287J?
K: 287 J
U: ? cal
287 J
1 cal x =
68.6 cal 1
4.184 J

10. Conversions between energy units:
Example: How many kJ are equal to 1478cal?
K: 1478cal
U: ? kJ
1478 cal
4.184 J
1 kJ x x =
6.184 kJ 1
1 cal
1000 J

11. Questions?
Complete WS 1