Specific heat capacity (c) = the amount of energy needed to raise the temperature of 1 kg of a substance by 1°C.
Units: J/kg°C.
ΔE = mcΔθ — change in thermal energy = mass × specific heat capacity × change in temperature.
Water has a high specific heat capacity (4200 J/kg°C) — it takes a lot of energy to heat up, making it ideal for central heating.
Sand/rock has a lower specific heat capacity — heats up and cools down faster.
Required Practical — measuring SHC
Equipment: metal block (known mass), heater, thermometer, joulemeter or ammeter + voltmeter + timer.
Energy supplied = power × time = V × I × t.
Plot temperature against time graph. Gradient × mass × SHC = power.
Main source of error: heat loss to surroundings → makes measured SHC too high.
Improvement: wrap block in insulation to reduce heat loss.
Exam questions — 3 questions · 10 marks
⚡ Extended questions included. Show all working for calculation questions. The AI marks against the real AQA mark scheme.
1 markSHC definitionAQA 8463 P1 style
What is the specific heat capacity of a material?
A The total amount of heat energy stored in 1 kg of the material
B The energy required to change the state of 1 kg of the material
C The energy needed to raise the temperature of 1 kg of the material by 1°C
D The rate at which the material transfers heat energy
4 marksSHC calculationAQA 8463 P1 style
A 2 kg block of aluminium (SHC = 900 J/kg°C) is heated from 20°C to 80°C. Calculate the energy transferred to the block. (2 marks)
A kettle uses 150,000 J to heat 1 kg of water from 20°C to 100°C. Calculate the specific heat capacity of water. (2 marks)
Hint: ΔE = mcΔθ. For (b) rearrange to c = ΔE ÷ (mΔθ). Remember Δθ = final temp − initial temp.
+40 XP
1 markWhy insulate the blockAQA 8463 P1 RPA style
In the specific heat capacity required practical, why should the metal block be wrapped in insulation?
A To prevent electricity from escaping through the block
B To reduce heat loss to the surroundings so more of the electrical energy heats the block, giving a more accurate result
C To prevent the thermometer from touching the heater