1. Thermal Energy and Matter
Chapter 16

2. Heat
Heat is the transfer of thermal energy from one object to another due to a temperature difference
Flows from hot object to cold object
Flow is spontaneous

3. Temperature Temperature Temperature scales
Temperature is the measure of kinetic energy of the particles in an object (atoms) due to their random motions through space
Particles transfer heat through collisions with other particles
High energy lose energy as heat
Low energy gain energy as heat
Temperature scales
Fahrenheit
Celsius
Kelvin

4. Thermal Energy
Thermal energy is the total potential and kinetic energy of all the particles in an object
Thermal energy depends on the mass, temperature, and phase (solid, liquid, or gas) of an object

5. Thermal Contraction and Expansion
Thermal expansion is an increase in the volume of a material due to a temperature increase
Particles move further apart as temperature increases

6. Specific Heat
Specific heat is the amount of heat needed to raise 1 gram of material by 1 °C
The lower the specific heat of a material the quicker it will increase in temperature when heated.

7. Specific Heat Q = heat (joules) m = mass (grams)
c = specific heat (J/g·°C)
ΔT = change in Temperature (°C)

8. Problem
An iron skillet has a mass of grams. The specific heat of iron is J/g•°C. How much heat must be absorbed to raise the skillet’s temperature by 95.0°C?

9. Problem
How much heat is needed to raise the temperature of g of water by 85.0°C?

10. Problem
How much heat is absorbed by a 750-g iron skillet when its temperature rises from 25°C to 125°C?

11. Problem
In setting up an aquarium, the heater transfers 1200 kJ of heat to 75,000 g of water. What is the increase in the water’s temperature? (Hint: Rearrange the specific heat formula to solve for ∆T.)

12. Problem
To release a diamond from its setting, a jeweler heats a 10.0-g silver ring by adding 23.5 J of heat. How much does the temperature of the silver increase?

13. Problem
What mass of water will change its temperature by 3.0°C when 525 J of heat is added to it?

14. Thermodynamics
Conduction is the transfer of thermal energy with no transfer of matter
The further the particles are away from another, the slower the transfer of heat
Gasses (slowest)
Liquids
Solids (fastest)

15. Thermodynamics Conductors Insulators
A material that conducts thermal energy well
Insulators
A material that conducts thermal energy poorly

16. Thermodynamics Convection Convection current
The transfer of thermal energy when particles of a fluid (liquid or gas) move from one place to another
Convection current
When a fluid circulates in a loop as it alternately heats up and cools down
Hot air rises and cold air sinks

17. Thermodynamics Radiation
The transfer of energy by waves moving through space
All objects radiate energy
As an object’s temperature increases, the rate at which it radiates energy increases

18. Thermodynamics
Thermodynamics is the study of conversions between thermal energy and other forms of energy
First law of Thermodynamics
Energy is conserved – energy cannot be created or destroyed, but converted into different forms
Second Law of Thermodynamics
Thermal energy can flow from colder objects to hotter objects only if work is done on the system
Third Law of Thermodynamics
Absolute zero cannot be reached

19. Heat Engines External Heat Engine Internal Combustion Engine
An engine that burns fuel outside the engine
Ex. A steam engine
Internal Combustion Engine
An engine that burns fuel inside the engine
Ex. Car engine