Knowledge Organiser: Specific Latent Heat
This topic summary covers Knowledge Organiser: Specific Latent Heat within Specific Latent Heat for GCSE Physics. Revise Specific Latent Heat in Particle Model for GCSE Physics with 13 exam-style questions and 30 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 12 of 12 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 12 of 12
Practice
13 questions
Recall
30 flashcards
Knowledge Organiser: Specific Latent Heat
Key Terms
- Specific latent heat (L): energy per kg for state change at constant temperature
- Fusion (Lf): solid ↔ liquid; for water = 334,000 J/kg
- Vaporisation (Lv): liquid ↔ gas; for water = 2,260,000 J/kg
- Latent: "hidden" — temperature does not change
Key Facts
- Temperature stays CONSTANT during state changes
- Energy goes into potential energy (bond breaking), not kinetic energy
- Lv > Lf because vaporisation fully breaks all bonds
- Steam burns release latent heat AND then cool — more damaging than boiling water
Key Equations
- E = mL (state change at constant temperature)
- E = mcΔT (temperature change within a state)
- L units: J/kg
- E in J, m in kg
Exam Tips
- Use E = mL for flat sections of heating curve
- Use E = mcΔT for sloped sections
- Always state temperature constant during latent heat
- Link bond-breaking to potential energy increase
Common Mistakes
- Saying temperature rises during latent heat: Temperature stays constant during a state change — all the energy goes into breaking bonds, not increasing kinetic energy
- Using the wrong equation: Use E = mL for state changes (flat part of graph); use E = mcΔT for temperature changes (sloped part) — mixing these up loses all marks
- Forgetting mass must be in kg: The equation E = mL requires mass in kg — if given in grams, divide by 1000 first
- Confusing latent heat of fusion and vaporisation: Lf = melting/freezing (solid↔liquid); Lv = boiling/condensing (liquid↔gas) — vaporisation requires much more energy
- Not explaining WHY temperature stays flat: Examiners want to hear that energy breaks intermolecular bonds and increases potential energy — not just "it stays constant"
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Practice Questions for Specific Latent Heat
What is specific latent heat?
During a state change, energy is being supplied to a substance but the temperature does not change. Explain where this energy goes.
Quick Recall Flashcards
13 questions on Specific Latent Heat — practise free
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