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