P1- 1.8

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P1- 1.8- SPECIFIC HEAT CAPACITY

When a substance is heated, its temperature depends on:

- The amount of energy supplied to it

- The mass of the substance

- What the substance is

THE SPECIFIC HEAT CAPACITY OF A SUBSTANCE is the energy needed or transferred to 1KG of the substance to raise its temperature by 1 degree

The unit for specific heat capacity is the joule per kilogram per degree Celsius

FOR A KNOWN CHANGE OF TEMPERATURE OF A KNOWN MASS OF A SUBSTANCE:

E = m × c × θ

E is energy transferred in joules- J

M is the mass in kilograms- KG

C is the specific heat capacity- J/KG degrees Celsius

θ is the change in temperature- Degree Celsius

TO FIND THE SPECIFIC HEAT CAPACITY:

C = E

----

m × θ

STORAGE HEATERS:

- Uses electricity at night to heat special bricks or concrete blocks in the heater

- Energy transfer from the bricks keeps the room warm

- The bricks have a high specific heat capacity

- They store lots of energy

- They warm up slowly when the heater element is on and cools down slowly when it is off

Electricity consumed at off-peak times is sometimes cheaper, so storage heaters are designed to be cost effective