Thermal Energy

1. Thermal Energy Milbank High School

2. Sec. 12.1Temperature and Thermal Energy • Objectives • Describe the nature of thermal energy • Define temperature and distinguish it from thermal energy • Use the Celsius and Kelvin temperature scales and convert one to the other • Define specific heat and calculate heat transfer

3. Thermodynamics • “The study of heat” • Kinetic-molecular theory • Thermal Energy • Overall energy of motion of the particles that make up an object • Temperature

4. Equilibrium/Thermometry • Conduction • Thermal Equilibrium • Thermometer

5. Celsius and Kelvin • Celsius • Water freezes at 0°C • Boils at 100°C • Kelvin • Water freezes at 273 K • Absolute Zero • -273°C • 0 K

6. Heat and Thermal Energy • Heat • The energy that flows between two objects as a result of a difference in temperature (Q) • Measured in Joules (energy) • Convection • Radiation • Specific Heat Q = mCΔT

7. Calorimetry • A device used to measure changes in thermal energy • Insulated • Conservation of Energy in a closed system • Example Problem • Heat Transfer in a Calorimeter

8. Review Concepts… • Temperature is proportional to the average ________________of its particles. • Thermal energy is the measure of ______________. • At absolute zero, ________________. • Can you take the temperature inside of a vacuum? • Which liquid would an ice cube cool faster, water or methanol? • Why do easily vaporized liquids, such as acetone and methanol, feel cool to the skin?

9. Sec. 12.2Change of State and Laws of Thermodynamics • Objectives • Define heats of fusion and vaporization • State the first and second laws of thermodynamics • Define heat engine, refrigerator, and heat pump • Define entropy

10. Change of State • Melting point • Boiling point • Heat of fusion Q = mHf • Heat of vaporization Q = mHv • Example Problem • Melting a Solid and Warming the Resulting Liquid

11. The First Law of Thermodynamics • Thermodynamics • The total increase in the thermal energy of a system is the sum of the work done on it and the heat added to it • Heat Engine

12. Refrigeration Refrigeration-- Cooling by evaporation. Compress & cool to liquefy a gas (outside the fridge) then boil it in a vacuum (inside the fridge) to absorb heat.

13. The Second Law of Thermodynamics • Entropy • Natural processes go in a direction that maintains or increases the total entropy on the universe • Things become more disordered

15. Review Concepts… • Can you add thermal energy to an object without increasing its temperature? • When wax freezes, is energy absorbed or released by the wax? • You are boiling pasta. Will it cook faster if the water is boiling vigorously or if it is boiling gently?

16. Review • The second law of thermodynamics states that natural processes go in a direction that maintains or increases total __________. • First law of thermodynamics says that _________ + _________=___________ • Heat of fusion • Heat of vaporization • The three types of thermal energy transfer are _________, _________, and _________.

17. Review • Entropy! • How does it relate to creation/evolution? • The entropy of the universe always ___________ (increases or decreases). • An internal combustion engine converts _________energy to ________ energy. • _________ ________ is the quantity of heat required to raise the temperature of one kilogram of a substance by one kelvin.

18. Review • What does the kinetic-molecular theory state? • _______________is the study of heat. • When using a thermometer, energy is transferred via a process called ____________.