Internal Energy and Specific Heat Capacity
Example 1
Why must you wrap your food in aluminum foil for a barbecue?
Example 2
The concept of calorie and joules
Example 3: The Melting point of solder.
Why is the melting point of solder with 38% Lead and 62% Tin?
A. 327 deg C
B. 232 deg C
B. 232 deg C
C. 183 deg C
D. 279.5 deg C
D. 279.5 deg C
Example 4
The Melting of ice. How long does a cup of ice takes to melt?
Boiling/Condensation and Specific Latent Heat of Vaporisation
Example 5
Heating of 1 kg of ice at -20C till it boils.
Mass of water = 1.0 kg
Quantity
|
Value
|
Energy needed
|
/ J
|
Ratio
|
The specific heat capacity of ice
|
2100 J/kgK
|
To melt ice from -20°C to 0°C
|
42000
|
1
|
Specific latent heat of fusion
|
3.36 x 105 J/kg
|
To melt all the ice
|
336000
|
8
|
The specific heat capacity of water
|
4200 J/kgK
|
To raise the temperature from 0 to 100°C
|
420000
|
10
|
Specific latent heat of vaporization
|
2.26 x 106 J/kg
|
To boil all the water
|
2260000
|
54
|
Using the data above, sketch a graph for the heating of ice from -20 degree Celcius to steam, given that the heater supplies heat at a constant rate.
Example 6
Which one will evaporate faster? Two ponds of different sizes but the same depths are exposed under the sun. Which of the ponds will dry up first?
- A. The smaller one, because there is a smaller volume.
- B. The bigger one, because there is a greater area.
- C. Both will dry up at the same time because area/unit volume is the same.
Example 7
Which cools a cup of coffee faster?
Adding milk immediately or wait for a while?
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