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HEAT CAPACITY & SPECIFIC HEAT CAPACITYTopic 11: Thermal Properties of Matter For GCE O-Levels Physics 5054
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HEAT CAPACITY &
SPECIFIC HEAT CAPACITYTOPIC 11: THERMAL PROPERTIES OF MATTER
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WHAT HAPPENS TO MATTER WHEN THERMAL ENERGY IS
APPLIED TO IT?
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OF THE MATTER
THERMAL ENERGY
CAN
Change the temperature
Change the state
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FOCUS ONCHANGING THE TEMPERATURE
OF THE SUBSTANCE
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WHAT DO WE KNOW?When heat is applied to a substance.
The temperature of the substance will increase.
Heat Energy Applied
Change in Temperature of
substance
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HEAT CAPACITYThe amount of heat energy needed to
increase the temperature of a substance by 1 Kelvin or by 1 degrees Celsius.
Heat Capacity
Heat Energy
Change in Temperature
QC =
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“100g of water requires 12 600J of thermal energy to raise it from
300C to 600C”
Calculate its heat capacity.
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“100g of water requires 12 600J of thermal energy to raise it from
300C to 600C”
Calculate the heat capacity for 1000g of water.
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The heavier the mass of the substance, more thermal energy needed to increase
the temperature by 1K, the bigger the heat capacity.
mQC
mQC
HEAT CAPACITY
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How can we compare the heat capacity of different materials more meaningfully ?
How much thermal energy do we need to increase the temperature of these substance ?
aluminium cooper
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EXAMINE THE HEAT CAPACITY PER UNIT MASS
OR SPECIFIC HEAT CAPACITY
OF THE SUBSTANCE
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SPECIFIC HEAT CAPACITYThe amount of thermal energy required to
raise the temperature of 1 kg of a substance by 1 K or 10C
Heat Energy Applied
Change in Temperature by
1 K or 1ºC1 kg
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SPECIFIC HEAT CAPACITYis a property of the material.
The SI unit of specific heat capacity is Jkg-1K-1
Each material has its own unique specific heat capacity.
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Copper
400 J/kgK
Brass
380 J/kgKAluminium
900 J/kgK
SPECIFIC HEAT
CAPACITIES
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Ice2100 J/kgK
Glass 670 J/kgK
Water
4200 J/kgK
SPECIFIC HEAT
CAPACITIES
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WHAT DOES THE VALUE FOR THE SPECIFIC HEAT
CAPACITY MEAN ?
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Copper
400 J/kgK
1 kg of Cooper requires 400J of thermal energy to increase
its temperature by 1K.
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Water
4200 J/kgK
1 kg of water requires 4200J of thermal energy to increase
its temperature by 1K.
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Ice2100 J/kgK
Brass
380 J/kgK
Which of the two substances will be easier to heat up?
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Aluminium
900 J/kgK
Glass 670 J/kgK
Which of the two substances will take longer time to heat up?
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The higher the specific heat capacity, more thermal energy is needed to increase its temperature by 1K.
SPECIFIC HEAT CAPACITY
m
Qc
m
Q c
For different substances of equal masses,
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SPECIFIC HEAT CAPACITYThe amount of thermal energy required to
raise the temperature of 1 kg of a substance by 1 K or 10C
Heat Capacity
Heat Energy
Change in Temperature
Qc =m
Mass
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Thermal Energy = Power X Time Taken
WHAT ARE THE SOURCES OF THERMAL ENERGY?
Bunsen Burner Electric Burner
= P x tQ Heater
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What is the amount of energy required to raise the temperature of 2 kg copper from 300C to 800C, given that the specific heat
capacity of copper is 400 Jkg-1 0C-1 ?
EXAMPLE EXERCISE 1
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EXAMPLE EXERCISE 1
Thermal Energy
MassSpecific Heat
CapacityChange in
Temperature= X X
Q c= mCu Cu Cu CuX X
= 2 kg 400 J/kgºC (80 - 30)ºCX X
=QCu Pre
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An electric kettle contains an immersion heater of power 2.0 kW. It takes 5 minutes to heat
2.0 kg of water from 300C to 1000C.
Assuming no energy is lost to the surrounding, what is the specific heat capacity of water?
EXAMPLE EXERCISE 2
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EXAMPLE EXERCISE 2
=
Thermal Energy supplied to water by heater
=Thermal Energy use to increase
temperature of the water
cmwater X XP X t = water waterheater
Q =heater Q water
= 2kg (100 - 30)ºCX XcX water2000W 300s
cwater
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0.3 kg of water at 100 0C is poured into a copper vessel of mass 0.1 kg at 300C.
What is the final temperature of water assuming there is no energy lost to the
surroundings?
EXAMPLE EXERCISE 3
Specific heat capacity of copper = 400 Jkg-1 0C-1 Specific heat capacity of water = 4200 Jkg-1 0C-1
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EXAMPLE EXERCISE 3
0.3 kg100 0C
0.1 kg300C
water copper
Initial Final
? 0C
water & copper
= 4200 J/kg0Cc water = 400 J/kg0C c Cu
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EXAMPLE EXERCISE 3
Thermal Energy lost by water
=Thermal Energy gained
by copper
Q =water Q copper
=mwater cwater water mCu c Cu Cu
=X X0.3kg 4200J/kg0C (100 - 0C) 0.1kg 400J/kg0C ( 0C- 30)XX
= Pre
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SUMMARIZATION
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QC =
The amount of thermal energy required to
increase the temperature of a substance by
1 K or 10C
“Heat Capacity, C”
Qc =m
The amount of thermal energy required to
increase the temperatureof 1 kg of a substance by
1 K or 10C
“Specific Heat Capacity, c”
J/kg0C J/kgK J/0C J/K
SUMMARIZATION
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Thermal Energy supplied to substance by heater
=Thermal Energy to increase
temperature of the substance
=
=
SUMMARIZATION
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Thermal Energy lost by Substance A
=Thermal Energy gained
by Substance B
=
=
The heavier the mass of the substance, more thermal energy needed to increase
the temperature by 1K, the bigger the heat capacity.
mQC
mQC
HEAT CAPACITY
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The higher the specific heat capacity, more thermal energy is needed to increase its temperature by 1K.
SPECIFIC HEAT CAPACITY
m
Qc
m
Q c
For different substances of equal masses,
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