1. Heat, Temperature, & Thermodynamics

2. Heat vs. Temperature Temperature Heat
Avg. Kinetic Energy of the particles
Measured in C, F, K
“hot” & “cold” are relative terms
Absolute zero is zero Kelvin
Heat
A form of energy
Measured in calories or Joules
There is no “coldness” energy
Any object with temperature above zero Kelvin has heat energy

3. Temperature Scales Fahrenheit, F – customary (english) temp. scale
Celsius, C – metric temp. scale
Kelvin, K – metric absolute zero temp. scale

4. Comparing Temperature Scales
(All temperatures listed are for water) °F °C K
boiling
212
100
373
freezing 32
273
Absolute zero
-460
-273
K = °C or °C = K - 273

5. Heat Transfer
Conduction - requires direct contact or particle to particle transfer of energy; usually occurs in solids
Convection - heat moves in currents; hot air rises and cold air falls; only occurs in fluids
3.Radiation - heat waves travel through empty space, no matter needed; sun

6. Thermal Equilibrium
A system is in thermal equilibrium when all of its parts are at the same temperature.
Heat transfers only from high to low temperatures and only until thermal equilibrium is reached.

7. Melting & Boiling Point
Melting or Freezing Point – the temperature at which a substance melts or freezes. Water: 0°C
Boiling or Condensation Point – the temperature at which a substance vaporizes or condenses. Water: 100°C
For other substances, refer to your chart.

8. Change of State Temp ° C Increasing Heat Energy (Joules)
steam
Increasing Heat Energy (Joules)
-20
100
ice
water
melting
vaporization
condensation
freezing
Heat of vaporization
Heat of fusion
Temp ° C
As heat is added to a substance it will either be absorbed to raise the temperature OR to change the state of matter.
It can NEVER do both at the same time!
Temperature will NOT change during a phase change!

11. Latent Heat the heat that goes into causing a change in state.
the energy needed to break the attraction between particles--does not increase the kinetic energy/temperature of substance.
Latent heat of vaporization
Evaporation – adding heat
Condensation – removing heat
Latent heat of fusion
Melting – adding heat
Freezing/Crystallization – removing heat

12. Specific Heat Capacity
The amount of heat energy needed to raise the temperature of 1 gram (or kg) of a substance by 1°C (or 1 K).
Substances with higher specific heats, such as water, change temperature more slowly.
Symbol : c units : cal/(g°C) or J/(kg°C)
For water: c = J/(g°C) = J/(kg°C)
or c = 1 cal/ (g°C)

13. Heat Calculations Q = mcΔT Temperature Change
Q = heat absorbed or released, J
m = mass of substance being heated, kg
c = specific heat of substance, J/(kg°C)
ΔT = change in temp.,°C or K

14. Thermal Expansion
Substances expand as they heat and contract as they cool.
The exception to this rule is water. As water is cooled from 4°C to 0°C, it expands which explains why ice floats (it is less dense than water).

15. Thermodynamics The study of changes in thermal properties of matter
Follows Law of Conservation of Energy

16. 0th Law of Thermodynamics
Heat will be transferred between objects until thermal equilibrium (same temperature) is reached.

17. 1st Law of 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.
ΔU = W + Q
ΔU = change in the thermal energy of the system
W = work done on the system (W = Fd or W=ΔK)
Q = heat added to the system
(Q is + if absorbed, Q is – if released)
*All measured in Joules*

18. Internal Energy (U)
The total energy based on the particles’ motion and mass of material.
A cup of water is taken out of a pool
The TEMPERATURE is the same for both
The INTERNAL ENERGY (U) is higher for the pool, because it has more mass

19. 2nd Law of Thermodynamics
Natural (spontaneous) processes tend to increase the total entropy (disorder) of the universe.
Entropy increases when heat is added to a body and decreases when heat is removed.
Heat flows naturally from hot to cold

20. 3rd law of Thermodynamics
As the temperature of an object approaches absolute zero (0 Kelvin), its entropy and kinetic energy approach zero.