Specific Heat Capacity

Basics
1. Materials which need to gain lots of energy to warm up also release lots of energy when cooling down – ‘store’ lots of heat.
2. When substance is heated, temp depends on:
  1. Amount of energy supplied to it
  2. Mass of substance
  3. What substance is
3. Specific heat capacity of a substance: energy needed/transferred to 1kg of substance needed to raise its temp by 1°C.
  1. Unit for specific heat capacity is joules per kg per °C.
4. Formula: E = m x c x θ
  1. Where E = energy transferred in J
  2. m = mass in kg
  3. c = specific heat capacity in J/kg °C
  4. θ = temp change in °C.
  5. To find specific heat capacity – rearrange equation: c = E/m x θ
Storage Heaters
1. Materials used in them usually have high specific heat capacities to store lots of energy.
2. Water has high specific heat capacity + is liquid so can be pumped in pipes – ideal for central heating.
3. Uses electricity at night (off-peak) to heat special bricks/concrete blocks in heater. Energy transfer from bricks keeps room warm – have high specific heat capacity - store lots of energy. Warm up slowly when heater element is on + cools slowly when off.
4. Some are filled with oil which has specific heat capacity that’s lower than water – often not as good as water -based systems.
  1. However oil does have higher boiling point – oil filled heaters can safely reach higher temps than water-based ones.
5. Electricity consumed at off-peak times sometimes charged at cheaper rate – storage heaters designed to be effective.

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Specific Heat Capacity

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