1. Agenda for 3/3/17 Heat Energy Notes Heat Problems
HW – keep working on PE/KE Lab type up

2. *
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Heat Energy *

3. Temperature Temperature -*
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Temperature
Temperature -
measure of the average KE of the particles in a sample of matter *

4. Temperature Conversions*
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Temperature Conversions
oC to oF: oF = 9/5oC + 32
oF to oC: oC = 5/9(oF – 32)
oC to K: K = oC + 273
K to oC: oC = K – 273 *

5. Thermal Energy Thermal Energy -*
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Thermal Energy
Thermal Energy -
the total energy (KE and PE) of the particles in a material
depends on temperature, mass, and type of substance *

6. Thermal Energy A B Which beaker of water has more thermal energy?*
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Thermal Energy
Which beaker of water has more thermal energy?
B - same temperature, more mass
200 mL
80ºC A
400 mL B *

7. *
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Heat Transfer
Heat - thermal energy that flows from a warmer material to a cooler material
Heat is always transferred from hot to cold
Ex. A warm soda with ice in it gets cooler (loses heat) because the heat from the soda is being transferred to the ice, causing ice to melt *

8. Heat Transfer A B Why does A feel hot and B feel cold?*
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Heat Transfer
Why does A feel hot and B feel cold?
Heat flows from A to your hand = hot.
Heat flows from your hand to B = cold.
80ºC A
10ºC B *

9. Heat Transfer Heat is transferred in 3 different ways – 1) conduction*
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Heat Transfer
Heat is transferred in 3 different ways –
1) conduction
2) convection
3) radiation *

10. *
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Specific Heat
Specific Heat (Cp) - the ability of matter to GAIN or LOSE heat
Each object has its own characteristic specific heat
These values are the amount of heat needed to raise the temperature of 1 g of water by 1°C
Compare the temperature of the metal part of your desk to your notebook. Which feels cooler? *

11. Heat Transfer Which sample will take longer to heat to 100°C? 50 g Al*
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Heat Transfer
Which sample will take longer to heat to 100°C?
50 g Al
50 g Cu
Al - It has a higher specific heat.
Al will also take longer to cool down. *

12. Q = m  T  Cp Heat Problems Q: heat (Cal)  units for heat*
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Heat Problems
Q = m  T  Cp
Q: heat (Cal)  units for heat
m: mass (g)
T: change in temperature (°C)
Cp: specific heat (Cal/g.oC)
– Q = heat loss
+ Q = heat gain
T = Tf - Ti *

13. Heat Problems Q = 32 x (20 - 60) x 0.0564 Q = 32 x -40 x 0.0564*
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Heat Problems
A 32-g silver spoon cools from 60°C to 20°C. How much heat is lost by the spoon?
Q = m x (final temp – initial temp) x Specific Heat
Q = 32 x ( ) x
Q = 32 x -40 x
Q = Cal *

14. Heat Problems
How many calories of heat must flow into 150 grams of water at 0° C to raise its temperature to 25° C?
Q = m x (final temp – initial temp) x Specific Heat
Q = 150 x (25 – 0) x 1.00
Q = 150 x 25 x 1
3,750 Calories

15. Conduction
The transfer of heat by direct contact between objects or particles.
Occurs best in solids
Transferred until equal

16. Convection
Heat transferred by the movement of molecules within a substance.
Movement occurs from warmer areas to cooler areas.

17. Convection Currents - The movement of a substance that is caused by differences in temperature and density.
EXAMPLES: wind, boiling water

20. Radiation Heat transferred through space.
Transferred in all directions.
No contact required!
Dark or dull objects absorb more than light or shiny objects do.
EXAMPLE: The sun’s rays causing a sunburn.

24. Agenda for 3/6/15 Go over quiz Finish Heat Energy Notes
Heat Energy Problems
No HW

25. Agenda for 3/9/15 Ticket in the Door Go over heat problems from Friday
Transfer of Heat Lab
HW – Finish Lab (if not completed in class) and More Heat Problems Worksheet