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Specific Heat Capacity

Heating a substance involves transferring energy after all heat is a form of energy. Specific heat capacity is the amount of energy required to raise the temperature of 1Kg of the substance by 1 degree Celsius.

As you can see from the table below each substance can vary in the amount of energy needed to raise it's temperature by 1°C per 1kg of mass.

Substance Specific heat capacity in J / kg °C
Aluminium 897
Copper 385
Glass 840
Gold 129
Iron 450
Lead 129
Oxygen 918
Silver 233
Water 4181

For an example from the table above, to heat 1kg of iron by 1°C you would need to transfer 450J of heat energy. Water can store many times more heat energy and would take a comparable massive 4181J to heat 1kg by 1°C. This makes water a very good substance to store heat energy and is why it is used in a majority of central heating systems to pump around the building into radiators, which as their name suggests radiate the heat energy into the surrounding area.

The greater the mass of the substance then the greater amount of energy needed to raise the temperature. For example a 5kg mass of iron would need 2250J (5 x 450J). Also the larger the mass the slower the heat transfer. Heating a 2kg mass of water would be much quicker than heating a 5kg mass.

Using the equation for specific heat capacity E=m x c x θ

E is energy
m is mass
c is specific heat capacity
θ is the temperature change

Lets work out how much energy it would take to raise the temperature of 5kg of aluminium from 22°C to 25°C.

E = m(5kg) x θ(3°C) x c(897)
E = 13455J

Here is a link to a Specific Heat Capacity Calculator to check your answers with.

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