Knowledge Organiser: Specific Heat Capacity
Key Terms
- SHC (c): energy to raise 1 kg of a substance by 1°C (J/kg°C)
- Δθ: temperature change = final − initial (°C)
- Thermal equilibrium: no net heat flow between objects
- Systematic error: consistent offset due to heat loss
Key Equation
- ΔE = mcΔθ
- c = ΔE / (mΔθ)
- Δθ = ΔE / (mc)
- Water SHC = 4200 J/kg°C
Key Facts
- High SHC = slow to heat/cool (stores lots of energy)
- Low SHC = heats up and cools quickly
- Experimental SHC always too HIGH (heat loss to surroundings)
- Water used in heating because of its very high SHC
Exam Tips
- Δθ is temperature CHANGE, not final temperature
- Mass in kg — convert from grams!
- Practical result too high → heat loss to surroundings
- Improvements: insulate block, oil in thermometer hole
Common Mistakes
- Using temperature instead of temperature change: ΔT is the change in temperature — not the final temperature reading
- Mass in grams not kg: The equation requires mass in kg — divide grams by 1000 before substituting
- Misidentifying the practical error: If the measured SHC is too high, energy was lost to surroundings (insulation poor), not gained
- Rearranging incorrectly: To find SHC: c = ΔE ÷ (m × ΔT) — divide by the product of m and ΔT, not just one of them
- Confusing SHC with latent heat: SHC applies when temperature changes; latent heat applies during a change of state (no temperature change)
Memory Aid
- Remember ΔE = mcΔθ as: "Energy Makes Change" — Energy = mass × c × change in temperature.
- To remember water's SHC of 4200: "Four Two Zero Zero — Water is a slow burner, needs 4200 joules per kilogram per degree."
- For the practical: the result is ALWAYS too HIGH because energy LEAKS to surroundings — think of a "leaky thermometer" losing heat.