1. EFFECTS OF HEAT

2. EFFECTS OF HEAT
Thermal Expansion
 Change in Temperature
 Phase Change


3. THERMAL EXPANSION
1st Effect of Heat

4. THERMAL EXPANSION
Addition of heat to a body may cause it to
expand and shrinks when heat is removed.
The expansion of objects can be observed in
solids, liquids and gases.
It is affected by several other factors.

5. THERMAL EXPANSION: SOLID

6. SOLIDS: LINEAR EXPANSION
Change in length of a solid due to a change
in its temperature
 Depends on three factors:

 original
length, Li
 change in temperature, ΔT
 type of material / coefficient of linear expansion,


7. SOLIDS: LINEAR EXPANSION
Operational Definition: ΔL =  Li ΔT
where:
ΔL = change in length ( Lf – Li )
Li = original/initial length
ΔT = change in temperature ( Tf - Ti )
 = coefficient of linear expansion
Temperature should be in °C or K, never °F
Unit of  : °C-1 or 1/°C read as “per degree”

8. COEFFICIENTS OF LINEAR EXPANSION
Material
Aluminum
α
22.2
Material
German silver
α
18.4
Material
Marble
α
9.8
Brass
18.7
Glass, hard
5.9
Nickel
13
Bronze
18
Gold
14.2
Platinum
9
Cement
10
Granite
7.9
Silicon
3
Cobalt
12
Iron, cast
10.4
Silver
19.5
Concrete
12
Iron, pure
12
Steel
13
Copper
16.6
Lead
28
Tin
23.4
Diamond
1.18
Manganese
22
Titanium
8.6

9. APPLICATIONS OF LINEAR EXPANSION
Operational Definition: ΔL =  Li ΔT
where:
)
ΔL = change in length ( Lf – Li )
Li = original/initial length
ΔT = change in temperature ( Tf - Ti
 = coefficient of linear expansion
Note: temperatures should be in °C or K
Unit of  : °C-1 or K-1

10. THERMAL EXPANSION: LIQUID
You will do better if you
keep me in a cool dry
place. *Winks*

11. THERMAL EXPANSION: LIQUIDS
Operational Definition: ΔV =  Vi ΔT
where: ΔV = change in volume ( Vf – Vi )
Vi = original/initial volume
ΔT = change in temperature ( Tf - Ti
)
 = coefficient of volume
expansion
Note: temperatures should be in °C or K
Unit of  : °C-1 or K-1

12. COEFFICIENTS OF VOLUMETRIC EXPANSION
Material
Acetone
β
1430
Material
Glycerine
β
500
Alcohol, ethyl
1090
Kerosene
1000
Alcohol, methyl
1180
Mercury
180
Ammonia
2450
Olive oil
700
Chloroform
1270
Petroleum
1000
Gasoline
1000
Water
2140

13. THERMAL EXPANSION: GASES
Don’t inflate me too
much… especially on
a hot day. 

14. THERMAL EXPANSION: GAS
Charles’s Law : (Recall Gas Laws,
Chemistry)
Vi / Vf = Ti/ Tf
Volume is directly proportional to temperature.
(at constant pressure and number of moles)
where: temperature should be in Kelvin

15. COEFFICIENT OF EXPANSION OF SOME MATERIALS
Material
SOLIDS
Aluminum
Brass
Copper
Concrete
Iron
Ordinary Grass
Steel
Tungsten
LIQUIDS
Ethyl Alcohol
Gasoline
Glycerin
Mercury
Water
GAS
Air
 (x 10-6/°C)
 (x 10-6/°C)
24
19
17
12
12
8.5
12
4.3
75
56
36
35
35
1100
950
500
180
210
3400

16. WORD PROBLEMS:
1.
2.
3.
Solid. A 1.0 m long aluminum rod is heated
from 30.°C to 50.°C. (a) By how much will it
expand? (b) What will its final length be?
Liquid. 75.0mL of ethyl alcohol at 10.°C is
heated to 47°C. What will its final volume
be?
Gas. 250.0mL of oxygen is collected at
27°C at a particular pressure. What volume
will the gas have at 35°C if the pressure
remains the same?

17. TEMPERATURE
CHANGE
2nd Effect of Heat

18. Temperature Change
When heat is added to a system, its
temperature increases.
 When heat is removed from a system, its
temperature decreases.


Factors that affect this temperature
change
 the
type of material, C
 amount of material, m
 amount of heat added or removed, ∆Q

19. Temperature Change

Specific Heat Capacity (c)
-

refers to the quantity of heat needed to raise the
temperature of one gram of a substance by 1 °C.
Operational Definition
∆Q = mc∆T
Where:
∆Q
m
c
∆T
is the heat required or supplied
mass of the substance
specific heat capacity of the substance
change in temperature

20. Specific Heat Capacity (J/kg·K)
Material
Gold
C
129
Material
C
Material
C
Granite
790
Wood
1700
Mercury
139.5
Sand
835
Steam
2080
Tin
227
Carbon dioxide
839
Ice
2110
Silver
233
Glass
840
Gasoline
2220
Copper
385
Concrete
880
Plastic
2302.7
Iron
450
Aluminum
897
Ethyl alcohol
2440
Steel
466
Oxygen
918
Paraffin wax
2500
Diamond
509.1
Air
1012
Water
4181.3

21. REVIEW

What is heat?
 Heat is the transfer of energy.

What are the different modes of heat transfer?
 conduction, convection and radiation

Heat transfers from _______ to _______.
 from an area of higher temperature

22. EXTENDING

What happens when two objects of different
temperature are made into contact?
 Heat will transfer from the hotter to colder object.

What happens to the hotter object?
 It gets colder because it loses energy when heat
transfers from it to the colder object.

What happens to the colder object?
 It gets hotter because it gains energy when heat
transfers from the hotter object to itself.

23. EXTENDING

Will the heat transfer continue forever or will it
eventually stop? If it will stop, when?
 Heat transfer will stop when they reach the same
temperature. This temperature is called
equilibrium temperature.

At what temperature will they have thermal
equilibrium?
 At a temperature between the initial temperatures
(not necessarily the average though)

24. EXTENDING

What happens when two objects of same
temperature are made into contact with each other?
 No heat transfer will occur.

25. Thermal Equilibrium

When two objects of different temperature
are made into contact, heat transfer will
occur.

Heat transfer will continue until both have
the same temperature. When this happens,
the two objects are now in thermal
equilibrium.

The final temperature at which heat transfer
stops is called the equilibrium

26. PHASE CHANGE
3rd Effect of Heat

27. Phase Change

Latent Heat - Addition of heat does not always
results to a change in temperature; this heat
could instead be used in changing the phase
of some materials. This heat, which cannot be
measured by thermometers, is called hidden
or latent heat.

There are two types of latent heat:
 Latent
heat of Fusion
 Latent heat of Vaporization

28. Latent Heat of Fusion ( hf )


heat needed to change 1 gram of a solid
substance into 1 gram of liquid w/o changing its
temperature
OPERATIONAL DEFINITION
hf = Hf / m or Hf = m hf
where:
hf = latent heat of fusion of material
m = mass of material
Hf = heat needed to change the material
from solid to liquid without
changing
temperature

29. Latent Heat of Vaporization ( hv
)
heat needed to change 1 gram of a liquid
substance into 1 gram of gas w/o changing its
temperature
 OPERATIONAL DEFINITION
hv = Hv / m or Hv = m hv
where:
hv = latent heat of vaporization of
material
m = mass of material
Hv = heat needed to change the
material
from liquid to gas without
changing
temperature


30. Example: How much heat is required to
change 100. g of ice at -20oC to 120oC of
steam?