1. Heat Objectives –Be able to distinguish between heat and temperature –Be able to explain thermal equilibrium –Identify the three ways heat can be transferred –Understand specific heat and latent heat

2. What is Temperature? Temperature is our measurement of the average kinetic energy found in the random motions and vibrations of countless atoms and molecules. Temperature is a way of quantifying the kinetic energy of these atoms and molecules. Temperature is Energy.

3. Maxwell-Boltzman Velocity Distribution Higher temperatures mean higher velocities for atoms and molecules

4. Heat Transfer Three Modes of Heat Transfer Radiation Convection Conduction

5. Radiation Energy transport via electromagnetic waves

6. Convection Energy transport by mass motion

7. Conduction Energy transport by vibrational translation The jostling of atoms and molecules in close proximity in a solid, especially one with high conductivity.

8. Specific Heat Q = m c  T Q = HEAT ENERGY m = mass  T = Temperature difference c = specific heat responsible for the thermal properties of the substance (Joules/kg/Celsius)  T = Q/mc

9. Specific Heat  T = Q/mc For a given amount of heat energy, say 10,000 Joules, what is the temperature change for 1 kg of water and 1 kg of sand? C sand = 838 J/kg o C C water = 4186 J/kg o C  T sand = 10,000/1(838) = 11.9 o C  T water = 10,000/1(4186) = 2.4 o C

10. Heat Energy

11. Changes of State Energy Increased and Absorbed by Substance: SOLID to LIQUIDMelting LIQUID to GASBoiling SOLID to GASSublimation Energy Decreased and Released by Substance: GAS to SOLIDDeposition GAS to LIQUIDCondensation LIQUID to SOLIDFreezing

12. Latent Heat

13. Latent Heat of Fusion Heat Energy required to convert solid to liquid LfLf

14. Latent Heat of Vaporization Heat Energy required to convert liquid to gas. LvLv

15. Melting  T = Q/mc Amount of heat energy needed to bring a 25 g ice block to a temperature of 50 o C? Starting Temp = 0 o C Ending Temp = 50 o C Q = heat needed to make transition from ice to water + heat needed to heat water from 0 to 50 o C Q = mL f + mc  T

16. Melting Ice  Q = m L f + m c  T Q = heat needed to make transition from ice to water + heat needed to heat water from 0 to 50 o C = 80 cal/g*(25 g)*(4.186 J/1000 Cal) + 25 g *4.186 J/g o C *(50-0 o C) = 8.37 J + 5230 J = 5238.4 J

17. Temperature Conversions CELCIUS C = 5/9 (F-32) FAHRENHEIT F = (9/5 C) + 32 ABSOLUTE or KELVIN K = C + 273