1. Chapter 9 HEAT Goals: Temperature vs Heat, Thermal Energy, Temperature conversions, Specific Heat Capacity, Phase changes and Latent Heat

2. Temperature Measure of average kinetic energy of particles Measure of average kinetic energy of particles atoms and molecules atoms and molecules Internal energy – energy of atomic motion that causes temperatures to rise U Internal energy – energy of atomic motion that causes temperatures to rise U Motion of particles can be: Motion of particles can be: Translational – linear monatomic gas Translational – linear monatomic gas Rotational – spinning molecular Rotational – spinning molecular Vibrational – back + forth molecular Vibrational – back + forth molecular

3. Thermal Expansion Occurs as a result of an increase of internal energy and motion of particles Occurs as a result of an increase of internal energy and motion of particles Kinetic Energy Kinetic Energy ex: side walk expansion groves and thermometers ex: side walk expansion groves and thermometers Dependent upon the type of material Dependent upon the type of material Thermal equilibrium – temperature indicates conditions are not changing Thermal equilibrium – temperature indicates conditions are not changing

4. Temperature Conversions Scales include: Fahrenheit, Celsius and Kelvin Scales include: Fahrenheit, Celsius and Kelvin F 32-212 C 0-100 K ab zero- ? F 32-212 C 0-100 K ab zero- ? T°F = (9/5 T°C) + 32 T°F = (9/5 T°C) + 32 T°C = 5/9 (T°F – 32) T°C = 5/9 (T°F – 32) K = °C + 273.15 K = °C + 273.15 °C = K – 273.15 °C = K – 273.15 -40°F = -40°C -40°F = -40°C Practice Problems A pg 303 Practice Problems A pg 303

5. Heat Thermal Energy that is transferred Thermal Energy that is transferred Cause of particle vibration or KE increase Cause of particle vibration or KE increase High to Low (heat movers) High to Low (heat movers) Depends upon: Depends upon: temperature mass specific heat capacity temperature mass specific heat capacity Units are Joules cal kcal Btu Therms Units are Joules cal kcal Btu Therms 4.186 J = 1 cal 4186 J = 1 kcal Btu = 1055 J Therm = 100,000 Btu 4.186 J = 1 cal 4186 J = 1 kcal Btu = 1055 J Therm = 100,000 Btu The greater the temperature difference the faster the rate of heat transfer The greater the temperature difference the faster the rate of heat transfer

6. Heat Transfer Conduction, Convection and Radiation Conduction, Convection and Radiation Conduction – heat transfer from particle to particle in contact most important in solids influenced by specific heat capacity Conduction – heat transfer from particle to particle in contact most important in solids influenced by specific heat capacity Convection – rising and sinking currents important in fluids Convection – rising and sinking currents important in fluids Radiation – electromagnetic waves in matter and through empty space Radiation – electromagnetic waves in matter and through empty space

7. Heat Transfer can cause a Phase change Phase change diagram displays Energy vs Temperature Phase change diagram displays Energy vs Temperature Solid – FP – heat of fusion – MP – Liquid - CP – heat of vaporization – BP – Gas as a substance is heated Solid – FP – heat of fusion – MP – Liquid - CP – heat of vaporization – BP – Gas as a substance is heated condensation = warming process evaporation = cooling process condensation = warming process evaporation = cooling process Q = m ΔT Cp H2O = 4189 J/kg°C Q = m ΔT Cp H2O = 4189 J/kg°C Calorimetry Lab Calorimetry Lab Problems on handout Problems on handout

8. Latent Heat Hidden Heat Hidden Heat water has a high heat capacity and can store much heat energy water has a high heat capacity and can store much heat energy heats of fusion and vaporization required to rearrange atoms and disrupt intermolecular forces heats of fusion and vaporization required to rearrange atoms and disrupt intermolecular forces

9. Just Think…………….. Just Think…………….. The extreme cold is not just an Arctic Blast The extreme cold is not just an Arctic Blast or a reason to be out of school for a week or a reason to be out of school for a week it is the absence of thermal energy it is the absence of thermal energy or HEAT or HEAT so………………………… so………………………… be Cool be Cool and don’t forget to read pages 298-308 and 313-317 and don’t forget to read pages 298-308 and 313-317