Curriculum
Science — Second Preparatory
Unit 1: Matter and Energy
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Unit 2: Matter and Chemical Reactions
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Unit 3: Energy Flow in Photosynthesis and Respiration
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Unit 4: Geological Processes
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Text lesson
Changes of State
Changes of State
Lesson summary
Lesson summary
- Matter changes state when it is heated or cooled, without changing its chemical composition.
- Melting, vaporisation and sublimation absorb heat. Freezing, condensation and deposition release heat.
- The temperature stays constant during a change of state. The heat gained or lost during the change is the latent heat.
- Evaporation happens from the surface at any temperature. Boiling happens throughout the liquid at the boiling point.
- Use Q = m × L for heat during a change of state, and Q = m × c × ΔT for heat that changes the temperature.
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