1. Ch 10 Heat
pgs

2. Phase Change
Calorimetry only works when substances do not change phase
Phase change – the physical change of a substance from one state to another at constant pressure

4. Phase Change Phase changes involve potential energy between particles
The farther apart the particles are, the more potential energy is present

5. Phase Change
Bonds can be broken by particles moving far away from each other
Bonds can be formed by particles moving closer together
Decreasing the Potential Energy by moving from high potential energy (large separation) to low potential energy (small separation) will Increase the Kinetic Energy

6. Heat of Fusion (Lf) Units of J/kg
Energy required to melt a substance goes into rearranging the molecules
Heat of Fusion – the energy per unit of mass transferred to change a substance from liquid to solid or solid to liquid at constant temperature and pressure

7. Heat of Fusion (Lf)

8. Heat of Vaporization (Lv)
Units of J/kg
Energy required to vaporize a substance mostly goes into separating the molecules
Heat of Vaporization – the energy per unit of mass transferred to change a substance from liquid to vapor or vapor to liquid at constant temperature and pressure

9. Heat of Vaporization (Lv)

10. Latent Heat (L)
More energy is required to vaporize a mass of substance than to melt it
Heat of Vaporization is greater than Heat of fusion
Latent Heat – energy per unit mass that is transferred during a phase change of a substance (both heat of vaporization and heat of fusion)

11. Latent Heat (L)
Units of J/kg

13. Controlling Heat
Thermal Conduction – energy is transferred as heat between objects through contact
Thermal Conductors – substances that rapidly transfer heat
Thermal Insulators – substances that slowly transfer heat

14. Controlling Heat
Convection – transfer of heat through the displacement of cold matter by hot matter
Involves pressure differences, conduction and buoyancy
Electromagnetic Radiation – reducing internal energy by radiating electromagnetic radiation
Does NOT involve matter

15. Clothing and Climate Cold Climates
Without proper insulation, the body will try to reach equilibrium with its surroundings
Hypothermia – lower pulse, blood pressure, respiration
Insulating materials retain energy for cold climates

16. Clothing and Climate Hot Climates
Evaporation aids energy transfer in hot climates
Heat exhaustion or heat stroke will result if the body’s temperature becomes too high

17. How much energy is removed when 10
How much energy is removed when 10.0 g of water is cooled from steam at 133.0°C to liquid at 53.0°C?