IGCSE 0625 · THERMAL · 2.2

Thermal properties & temperature

Thermal expansion, specific heat capacity, changes of state and latent heat, and evaporation. It builds directly on the particle model and on energy and mass, and feeds into how energy is transferred.

TOPIC 2.2: THERMAL PROPERTIES & TEMPERATURE CAMBRIDGE IGCSE PHYSICS 0625 · PATHWAYS TheLucidSTEM · thelucidstem.com BUILDS ON 2.1 Particle model 1.7 Energy 1.3 Mass LEADS TO 2.3 Energy transfer Heating & cooling systems THERMAL PROPERTIES 1 · THERMAL EXPANSION Heating makes particles vibrate more and move a little further apart, so materials expand. Gases expand most, then liquids, then solids. Used in liquid-in-glass thermometers. Gaps are left in bridges and railway lines. cool: flat hot: bends toward the metal that expands less bimetallic strip 2 · SPECIFIC HEAT CAPACITY EXTENDED The energy needed to raise the temperature of 1 kg of a substance by 1 °C. E = m c Δθ Δθ = change in temperature metal block thermometer energy in 3 · MELTING, BOILING & LATENT HEAT During a change of state the temperature stays constant: energy goes into breaking bonds. θ time melting boiling The energy moved in a change of state: E = m L L = latent heat (Extended) 4 · EVAPORATION EXTENDED Evaporation happens from the surface of a liquid at any temperature, not just at boiling. fastest molecule escapes The fastest molecules leave, so the average energy left falls and the liquid cools. Faster when hotter, with more surface area, a draught, and drier (less humid) air.
TOPIC 2.2: THERMAL PROPERTIES & TEMPERATURE CAMBRIDGE IGCSE PHYSICS 0625 · PATHWAYS TheLucidSTEM · thelucidstem.com BUILDS ON 2.1 Particle model 1.7 Energy 1.3 Mass LEADS TO 2.3 Energy transfer Heating & cooling systems THERMAL PROPERTIES 1 · THERMAL EXPANSION Heating makes particles vibrate more and move a little further apart, so materials expand. Gases expand most, then liquids, then solids. Used in liquid-in-glass thermometers. Gaps are left in bridges and railway lines. cool: flat hot: bends toward the metal that expands less bimetallic strip 2 · SPECIFIC HEAT CAPACITY EXTENDED The energy needed to raise the temperature of 1 kg of a substance by 1 °C. E = m c Δθ Δθ = change in temperature metal block thermometer energy in 3 · MELTING, BOILING & LATENT HEAT During a change of state the temperature stays constant: energy goes into breaking bonds. θ time melting boiling The energy moved in a change of state: E = m L L = latent heat (Extended) 4 · EVAPORATION EXTENDED Evaporation happens from the surface of a liquid at any temperature, not just at boiling. fastest molecule escapes The fastest molecules leave, so the average energy left falls and the liquid cools. Faster when hotter, with more surface area, a draught, and drier (less humid) air.
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