1. Energy
Unit 1

2. States of Matter

3. Changing State of Matter

4. Changing States of Matter
In order to go from 1 state of matter to another, it involves energy (usually heat energy- enthalpy)
You are either removing the energy or adding more energy

5. Endothermic Processes
How does heat move? From areas of higher temperature to lower temperature!
Endothermic Processes
Exothermic Processes
Occur when heat is added to the system
Examples
Cooking
Evaporation
Instant cold packs
Occur when heat is given off by the system
Examples
Instant heat packs
Nuclear fission
Candle burning

6. Exothermic or Endothermic?

7. What is HEAT?
It’s the flow of energy due to a difference in temperature.
From a higher temperature (higher kinetic energy) to a lower temperature (less kinetic energy)
THERE IS NO SUCH THING AS COLD!
It’s just the absence of heat!
What is temperature?
It’s the average amount of kinetic energy a substance has from its moving atoms/ molecules
Kinetic energy is the energy of motion!

8. q = mCΔT Equation change in temperature, measured in °C
ΔT = Tfinal – Tinitial
heat energy – measured in joules (J)
heat capacity – how much heat a substance can hold, measured in joules/gramdegrees Celsius
mass - measured in grams (g)

9. Units for heat (q)
Most food tells us the amount of energy in units of Calories
Calories are kilocalories (1 Cal = 1000cal)
The SI unit for energy is Joules (J)
1 cal = J
Let’s do some quick conversions.

10. How can you tell if a process is endothermic or exothermic?
q is a positive number
Why?
The final temperature is higher than the initial temperature- we added heat to the system.
ΔT = Tfinal – Tinitial
q is a negative number
Why?
The final temperature is lower than the initial temperature- heat was given off from the system.
ΔT = Tfinal – Tinitial
Let’s solve some problems!