1. 1.3 Heat capacity and specific heat capacity
A magic balloon
Heat capacity
Specific heat capacity
‘Mixtures’
Importance of high specific heat capacity of water
Check-point 3 ? 1 2 ? ? 3 4
1.3 Heat capacity and specific heat capacity

2. A magic balloon WHY? Video Why the balloon did not pop?
1.3 Heat capacity and specific heat capacity

3. The balloon was filled with water.
A magic balloon
It is because…
The balloon was filled with water.
But…
Why can the water prevent the balloon from popping?
1.3 Heat capacity and specific heat capacity

4. Which one heats up faster?
1 Heat capacity
Which one heats up faster?
1.3 Heat capacity and specific heat capacity

5. 1 Heat capacity
Energy transferred by heating needed to raise the temp. through 1 C
Unit: J °C1
In equation:
E = CT
1.3 Heat capacity and specific heat capacity

6. 1 Heat capacity
1.3 Heat capacity and specific heat capacity

7. 2 Specific heat capacity
a Meaning of specific heat capacity
Different substances require different amounts of energy to heat it up.
They have different specific heat capacity c.
E = mcT
proportionality constant
1.3 Heat capacity and specific heat capacity

8. a Meaning of specific heat capacity
Energy transferred
by heating
needed
to raise
the temperature of
1 kg of the substance
through 1 °C.
Unit: J kg1 °C1
1.3 Heat capacity and specific heat capacity

9. a Meaning of specific heat capacity
Sometimes,
People prefer to talk about the heat capacity C of the whole body rather than 1 kg of it.
This is the energy to raise the temperature of the substance through 1 C.
Heat capacity = mass × specific heat capacity Or
C = m × c
1.3 Heat capacity and specific heat capacity

10. Comparing specific heat capacity with heat capacity
symbol: c
symbol: C
same for the same material
same for the same material of the same mass
E = mcT
E = CT
unit: J C1 or J K1
unit: J kg1 C1
or J kg1 K1
1.3 Heat capacity and specific heat capacity

11. a Meaning of specific heat capacity
1.3 Heat capacity and specific heat capacity

12. Experiment 1a Find out how much: energy The mass of water
Specific heat capacity
Find out how much:
energy
The mass of water
Temperature change
1.3 Heat capacity and specific heat capacity

13. Experiment 1a Video Video Specific heat capacity
1.3 Heat capacity and specific heat capacity

14. a Meaning of specific heat capacity
Based on experiment 1a,
When energy E is plotted against temperature change T,
a straight line is obtained.
E  T, for constant mass
1.3 Heat capacity and specific heat capacity

15. a Meaning of specific heat capacity
When energy E is plotted against the mass m,
a straight line is obtained.
E  m, for constant T
1.3 Heat capacity and specific heat capacity

16. a Meaning of specific heat capacity
Combining the two results,
E  mT
This means:
The energy needed to heat up the water is directly proportional to the
(1) mass of water and
(2) the temperature change.
It is true for all substances.
1.3 Heat capacity and specific heat capacity

17. b Specific heat capacities of some substances
c / J kg1 C1
Water
Glass
Copper
4200
600
370
Paraffin
Mercury
2200
140
Very high!
Can you tell what it means?
1.3 Heat capacity and specific heat capacity

18. c How is specific heat capacity is measured?
1.3 Heat capacity and specific heat capacity

19. How much energy is needed?
Experiment 1b
Measuring the specific heat capacity of water
Set-up the apparatus.
- mass of water = 0.2 kg
- heat up by 10 °C
How much energy is needed?
Video
Simulation
1.3 Heat capacity and specific heat capacity

20. Precautions: 1 Switch on the heater...
…unless the heating part of it is totally immersed in water.
Totally immerse the heating part of the heater in water. 2
3 Take the final temperature as soon as the power supply is switched off.
Stir the water and record the highest reading.
1.3 Heat capacity and specific heat capacity

21. c How is specific heat capacity is measured?
1.3 Heat capacity and specific heat capacity

22. How much energy is needed?
Experiment 1c
Measuring the specific heat capacity of aluminium
How much energy is needed?
Video
Simulation
1.3 Heat capacity and specific heat capacity

23. Precautions:
1 Add a few drops of oil to the holes in the aluminium block.
Place the aluminium block on a polystyrene tile. 2
3 Switch on the heater...
…unless the heating part of it is in contact with the aluminium block.
1.3 Heat capacity and specific heat capacity

24. 3 ‘Mixtures’
When two bodies that have different temperatures are put in contact,
energy is transferred from the hot body to the cold body.
energy lost by the hot body
energy gained by the cold body =
1.3 Heat capacity and specific heat capacity

25. 3 ‘Mixtures’ Energy flows from hot body to cold body
After a certain time
high
low
same
Energy flows from hot body to cold body
Transfer of energy stops
1.3 Heat capacity and specific heat capacity

26. 3 ‘Mixtures’ It agrees with conservation of energy.
The conservation of energy:
The total amount of energy in a system is conserved
1.3 Heat capacity and specific heat capacity

27. 3 ‘Mixtures’
1.3 Heat capacity and specific heat capacity

28. Experiment 1d
‘Mixture’
Measure the mass and temperature of a cup of cold water and those of a cup of hot water.
Quickly mix the 2 cups of water and measure the temperature of the ‘mixture’.
Video
1.3 Heat capacity and specific heat capacity

29. 4 Importance of high specific heat capacity of water
Video
The high specific capacity if water makes it useful.
1.3 Heat capacity and specific heat capacity

30. 4 Importance of high specific heat capacity of water
Water has a very high specific heat capacity.
Water can take in a lot of energy with only a small temperature rise.
 Coolant in motor cars
1.3 Heat capacity and specific heat capacity

31. Heat removed from engine Energy given out by radiator
air flows
pump
a Water takes in energy from the hot engine and carries it to the radiator and releases it to the air.
1.3 Heat capacity and specific heat capacity

32. 4 High specific heat capacity of water
b The temperature of sea-water rises and falls much more slowly than that of the land.
It is because the small temperature change of the sea.
1.3 Heat capacity and specific heat capacity

33. 4 High specific heat capacity of water
c The watery fluids in the human body have a high specific heat capacity. (approx. 70%)
Though temperature of the surroundings changes …
temperature of body changes slowly.
1.3 Heat capacity and specific heat capacity

34. Check-point 3 1 When 9000 J is given to a…
2 Heat sink is a device for…
3 Calculate the amount of…
4 When 6750 J is given to 3 kg…
5 Amy is preparing an…
1.3 Heat capacity and specific heat capacity

35. (Specific heat capacity of aluminium = 900 J kg1 C1)
Check-point 3 – Q1
When 9000 J is given to a 1-kg aluminium block, what is the temperature increase of the block?
(Specific heat capacity of aluminium = 900 J kg1 C1)
A 1 °C
B 5 °C
C 10 °C
D 20 °C
1.3 Heat capacity and specific heat capacity

36. Which of the following is/are true for a good heat sink?
Check-point 3 – Q2
Heat sink is a device for absorbing and dissipating heat.
Which of the following is/are true for a good heat sink?
A It has high specific heat capacity.
B It has large surface area.
C All of the above.
1.3 Heat capacity and specific heat capacity

37. (Heat capacity of the glass of milk = 2400 J C1)
Check-point 3 – Q3
Calculate the amount of energy required to heat up a glass of milk from 20 °C to 60 °C.
(Heat capacity of the glass of milk = 2400 J C1)
Energy required E = CT
(60  20)
2400
= _______ x _________ J
= _______
1.3 Heat capacity and specific heat capacity

38. What are the specific heat capacity of this block?
Check-point 3 – Q4
When 6750 J is given to a 3 kg of a metal block, the temperature of the block rises by 5 °C.
What are the specific heat capacity of this block?
Specific heat capacity
c = E/mDT
c = 6750/( )
= ______________
3  5
450 J kg1 °C1
1.3 Heat capacity and specific heat capacity

39. Check-point 3 – Q4 Heat capacity = mc = _________ 1350 J K1
1.3 Heat capacity and specific heat capacity

40. What will be the temperature of the mixture just after mixing?
Check-point 3 – Q5
Amy is preparing an instant cup noodle by adding 200 g of water at 90 °C to 80 g of noodle at 20 °C.
What will be the temperature of the mixture just after mixing?
(Specific heat capacities of water and noodle are 4200 J kg1 °C1 and 2000 J kg1 °C1 respectively)
1.3 Heat capacity and specific heat capacity

41. Let T be the temp. of mixture.
Check-point 3 – Q5
Let T be the temp. of mixture.
Energy lost by hot water
Energy gained by noodle =
0.2 x 4200 x (90 – T )
0.08 x 2000 x (T – 20)
_________________ = ___________________
78.8 °C
T = _______
1.3 Heat capacity and specific heat capacity

42. The End
1.3 Heat capacity and specific heat capacity

43. Example 3 In order to heat up the water from 20 C to 25 C in
Heat capacity of the water
In order to heat up the water from 20 C to 25 C in
(a) a glass (Fig a), 4.2 kJ of energy is needed.
Fig a
(b) An indoor swimming pool (Fig b), 5.25 x 107 kJ of energy is needed.
Fig b
What are the heat capacities of the water in the above two cases?
1.3 Heat capacity and specific heat capacity

44. Example 3 (a) E C = T 4200 J = (25  20) C = 840 J C1
Heat capacity of the water
(a) E C = T
4200 J =
(25  20) C
= 840 J C1
The heat capacity of the water in a glass is 840 J C1
1.3 Heat capacity and specific heat capacity

45. Example 3 (b) E C = T 5.25 x 1010 J = (25  20) C
Heat capacity of the water
(b) E C = T
5.25 x 1010 J =
(25  20) C
= 1.05 x 1010 J C1
The heat capacity of the water in a swimming pool is 1.05 x 1010 J C1
1.3 Heat capacity and specific heat capacity

46. Return
1.3 Heat capacity and specific heat capacity

47. Example 4 Calculate the energy needed to raise the temperature...
Energy needed to raise temperature
Calculate the energy needed to raise the temperature...
...of 5 kg of aluminum from 20 C to 100 C.
Specific heat capacity of aluminium is 900 J kg1 C1.
1.3 Heat capacity and specific heat capacity

48. Example 4 The energy needed is: E = mcT = 5  900  (100  20)
Energy needed to raise temperature
The energy needed is:
E = mcT
= 5  900  (100  20)
= J
1.3 Heat capacity and specific heat capacity

49. Return
1.3 Heat capacity and specific heat capacity

50. Example 5 In the experiment, the results are: Mass of water = 0.2 kg
Specific heat capacity of water
In the experiment, the results are:
Mass of water = 0.2 kg
Initial joulemeter reading = J
Final joulemeter reading = J
Initial temperature = 20 C
Final temperature = 37 C
1.3 Heat capacity and specific heat capacity

51. Example 5 Find (a) Find the specific heat capacity of water.
(b) Account for any difference of the value from the standard value, 4200 J kg1 C1
1.3 Heat capacity and specific heat capacity

52. Example 5 (a) c = E/mT = (61 000 – 46 000) / [0.2 × (37 – 20)]
Specific heat capacity of water
(a) c = E/mT
= ( – ) / [0.2 × (37 – 20)]
= 4410 J kg1 C1
1.3 Heat capacity and specific heat capacity

53. Example 5 (b) There is 5% error.
Specific heat capacity of water
(b) There is 5% error.
The error is due to energy loss to the surroundings.
Some energy is transferred to heat up the cup, stirrer and thermometer.
1.3 Heat capacity and specific heat capacity

54. Return
1.3 Heat capacity and specific heat capacity

55. Example 6 The experiment results were obtained:
Specific heat capacity of aluminium
The experiment results were obtained:
Mass of aluminium = 1.0 kg
Initial & final temperature = 28.5 oC, 35 oC
Initial joulemeter reading = J
Final joulemeter reading = J
1.3 Heat capacity and specific heat capacity

56. Example 6 (a) Find the specific heat capacity of aluminium.
c = E / (m T )
c = (  )/ [1 × (35  28.5) ]
= 1020 J kg1 oC1
1.3 Heat capacity and specific heat capacity

57. Example 6
Specific heat capacity of aluminium
(b) Account for any difference from the standard value, 900 J kg1 C1
Compared with the standard value of 900 J kg1 oC1, there is an error of about 13 %.
1020  900
900
= 0.13 = 13%
× 100%
This error is due to the energy loss to the surroundings.
1.3 Heat capacity and specific heat capacity

58. Return
1.3 Heat capacity and specific heat capacity

59. Example 7
Temperature of mixture
0.3 kg
10 C
0.4 kg
80 C
What is the temperature of the ‘mixture’?
1.3 Heat capacity and specific heat capacity

60. Example 7 Let T be the temperature of the mixture.
Temperature of mixture
Let T be the temperature of the mixture.
Fall in temperature of hot water
= (80 – T ) C
0.7 kg
T C
Rise in temperature of cold water
= (T – 10) C
1.3 Heat capacity and specific heat capacity

61. Example 7 Assuming no energy is lost to the surroundings
Temperature of mixture
Assuming no energy is lost to the surroundings
energy gained by cold water
energy lost by hot water =
0.4 × 4200 × (80 – T ) = 0.3 × 4200 × (T – 10)
0.4 × (80 – T ) = 0.3 × (T – 10)
Solving the equation, T = 50 °C
1.3 Heat capacity and specific heat capacity

62. Return
1.3 Heat capacity and specific heat capacity