1. Energy and energy transformations
Thermodynamics
Energy and energy transformations

2. First Law of Thermodynamics
Energy is never created nor destroyed
Energy can change forms, but the quantity is always constant.

3. Second Law of Thermodynamics
The Entropy of the Universe is always increasing
Entropy= disorder

4. Third Law of Thermodynamics
The entropy of an ideal solid at zero Kelvin is zero
All molecular motion stops at 0 K

5. Heat vs. Temperature

6. Temperature and Heat
Temperature is the measurement of the avg. KE of the molecules in a material.
Heat is the transfer of KE from one material to another.
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7. Heat flows
from WARMER to
COLDER!

8. How does heat effect temperature?
Adding Energy (heat) TO a substance causes its
Temperature to go UP!
Taking energy (heat) AWAY from a substance causes its
- Temperature to go DOWN!

9. How does heat effect temperature?
Adding Energy (heat) TO a substance causes its
Temperature to go UP!
Taking energy (heat) AWAY from a substance causes its
- Temperature to go DOWN!

10. How does heat effect temperature?
Box A : Has more energy (heat) – Has a higher temperature
Box B : Has less energy (heat) – Has a lower temperature
When they are combined
- Box A loses (releases) heat – temperature goes down (= to B)
- Box B gains (absorbs) heat – temperature goes up ( = to A)

11. Heat vs Temperature Temperature - measure of average KE
Heat - measure of energy transfer
Temp change (∆T) depends on:
amount of heat transferred (q)
mass of object (m)
specific heat of the object (C)
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12. Specific heat

13. Have you ever noticed that on a hot summer day the ocean is cooler than the hot sand? Why? The sun has been beating down on both of them for the same amount of time
Heat (radiation)
Heat (radiation)
Why aren't they the same temperature?
cool
hot

14. It takes MORE thermal energy to raise the temperature of water than the sand!
Water has a higher SPECIFIC HEAT that sand!

15. Specific Heat
The amount of energy required to raise the temperature of a material (substance).
It takes different amounts of energy to make the same temp change in different substances.
We call the amount required: Specific Heat!

16. Water needs a lot of heat energy before its temperature changes
Sand/ cement need a little heat energy before its temperature increases.

17. Specific Heat Table
The lower the specific heat – the easier (faster) it is to heat up and cool down.
The higher the specific heat – the harder (slower) it is to heat up and cool down.
Which substance would lose its heat fastest?
Which substance would take longer to heat up?

18. Calculating Specific Heat
The Greek letter Δ means “change in”

19. Measuring Heat q = m C ∆T q = heat
measured in joules (J) or kilojoules (kJ)
1000J = 1kJ
m = mass; measured in grams (g)
∆ T = change in temp
measured in Celsius (°C) or Kelvin (K)
C = specific heat
units are J/g°C or J/gK