GCSE›AQA GCSE Physics›Mind mapsChanges of State and Internal EnergyAQA GCSE Physics: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsInternal energyTotal kinetic + potential energy of all particlesKinetic: energy of random motionPotential: energy from particle separation and bondsHeating raises kinetic (faster) or potential (further apart)Melting, freezingSolid → liquid is melting; reverse is freezingMelting: energy breaks some forces, particles move past each otherFreezing: particles slow, forces hold them fixedTemperature stays constant during the changeBoiling, condensingLiquid → gas is evaporation; reverse is condensationAlmost all forces broken, particles spread far apartEnergy goes into bonds, not kinetic energyTemperature stays constant here tooChanges of stateand internal energyQ=mLQ = mLQ=mLJkgJ/kgSublimationSolid → gas directly, no liquid stageReverse is depositionExample: dry ice (solid CO₂)Latent heatEnergy to change state of 1 kg without temperature changeQ=mLQ = mLQ=mLFusion: melting or freezingVaporisation: evaporating or condensingVaporisation is always larger than fusion2 kg water: 2×2 260 000=4.52 MJ2 \times 2\,260\,000 = 4.52\,\text{MJ}2×2260000=4.52MJExam tipsExplain internal energy as two partsNo temperature rise does not mean no energy transferPick fusion or vaporisation from the change describedShow formula, substitution and units