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1kg of water
230C
A B 1kg of 4kg of water water
2kgAl
4kgAl 4kg
Pb
Figure below shows three objects with different heat capacities because different amounts of heat are required to raise their temperature by 10C.
10C increase in temperature
10C increase in temperature
10C increase in temperature
1800 J of heat
3600 J of heat520 J of heat
Although A and B are both made from aluminium, they have different heat capaties because the masses are different.
It is because the metal and plastic have different heat capacity
The specific heat capacity of a substance is the amount of heat that must be supplied to increase the temperature 10C for a mass of 1kg of the substance
The formula for specific heat capacity is given by
Therefore, the quantity of heat absorbed or lost from a body is given by
Substance Specific heat capacity, c (J.kg-1°C-1)
SolidsIce (at -15°C)AluminiumGlassIronCopperSilverLead
2000900840452387235128
LiquidsWater (at 15°C)Ethyl alcoholBenzene
420024502410
GasSteam 2010
Some substances have higher specific heat capacities than others. Table below lists the specific heat capacities of some common
How much heat energy required to raise the temperature of a 3kg sheet of glass from 240C to 360C?
Specific capacity of glass = 840 J Kg-1C-1 .
Answer :
Given m= 3kg change in temperature =36-24=120CUsing Q= mcθ
Heat energy required, Q
Q= mcθ = 3 x 840 x 12 = 30 240 J
The bulb of a thermometer contains 3.4g mercury. What amount of heat required to raise the temperature of the mercury from 300C to 1000C?
Answer: 33 J
When an object is heated by an electrical heater of power, P ,over a period of time, t, the amount of heat energy supplied is given by
Q=Pt
The formula
Q = mcθ become Pt = mcθ