Specific Heat Capacity Objectives What is the difference between heat and temperature? What is specific heat capacity? How is it calculated? How is it useful? Why do you have to be careful with one of these?

Caution: Hot Apple Pie! Have you bitten into an apple pie and burnt your mouth? The outside is warm but the inside is very hot. It was all cooked together so why does this happen? It’s because the filling has a higher heat capacity than the pastry.

Heat vs Temperature What is the difference? Watch this video and write down the definitions. HEAT: _____________________________ TEMPERATURE:_____________________ The thermal energy contained in an object A measure of how hot something is When heat energy is transferred to an object, its temperature will increase

What is specific heat capacity? http://www.youtube.com/watch?v=D3CwpfBzF94 What is specific heat capacity? This is a measure of how much energy a material can store. It is the energy needed to raise the temperature of 1kg of a material by 1oC. It is measured in J/kg oC If we heated these materials for 10 minutes , which would get hottest? copper limestone water

SHC of different materials 82oC 43oC 65oC The copper became hottest because it has the lowest SHC. The water has the highest SHC as it absorbed the energy without becoming very hot.

Different materials Material Specific heat capacity (J/kg oC) Water 4200 Oil 2000 Limestone 910 Glass 840 Iron 460 Copper 390 Which would get hottest? 1kg of glass or 1kg of iron? Which material is used to heat radiators? Why? What other materials could be used in heaters? Which would feel colder after 1 hour in the fridge – limestone or copper?

Calculating specific heat capacity Can be calculated using this equation: ΔE = m x Δθ x c ΔE is the energy transferred in joules, J m is the mass of the substances in kg Δθ (‘theta’) is the temperature change in degrees Celsius, °C c is the specific heat capacity in J / kg °C

specific heat capacity Rearranging the equation: ΔE ΔE ΔE m = Δθ = c = c x Δθ c x m c x Δθ Energy transferred (J) temperature change oC specific heat capacity J/kg oC mass kg x x

specific heat capacity Rearranging the equation: ΔE ΔE ΔE m = Δθ = c = c x Δθ c x m c x Δθ Energy transferred (J) temperature change oC specific heat capacity J/kg oC mass kg x x

specific heat capacity Rearranging the equation: ΔE ΔE ΔE m = Δθ = c = c x Δθ c x m c x Δθ Energy transferred (J) temperature change oC specific heat capacity J/kg oC mass kg x x

Examples – show your working E = m x θ x c For example, how much energy must be transferred to raise the temperature of 2 kg of water from 20°C to 30°C? How much energy is needed to raise the temperature of 1 kg of glass from 30°C to 45°C? How much energy is needed to increase the temperature of 500 g of lead from 20°C to 45°C? The specific heat capacity of lead is 128 J/kg °C.

Frying an egg in paper Can you fry an egg in newspaper? Watch the clip. Can you explain how it works?