Edexcel GCSE Physics 1PH0
Key Concepts of Physics
Motion and Forces
Conservation of Energy
Waves
Light and the Electromagnetic Spectrum
Radioactivity
Astronomy
Energy – Forces Doing Work
Forces and Their Effects
Electricity and Circuits
Static Electricity
Magnetism and the Motor Effect
Electromagnetic Induction
Particle Model
Forces and Matter
Particle Model
Specific latent heat and thermal insulation
- 3 things to know
- Paper 2
Overview
The energy for a change of state from mass and specific latent heat, calculations for melting and boiling, and how trapped air, double glazing, loft insulation, foam and shiny surfaces reduce energy transfer.
What you need to know
Answer each one before you reveal it.
State the equation for the thermal energy needed for a change of state.
Calculate the energy needed to melt 0.50 kg of ice at 0 °C, given a specific latent heat of fusion of 3.34 × 10⁵ J/kg.
Questions from this subtopic
Each one with the model answer underneath.
- 1
State the equation for the thermal energy needed for a change of state.
Model answer
Thermal energy = mass × specific latent heat.
- 2
Calculate the energy needed to melt 0.50 kg of ice at 0 °C, given a specific latent heat of fusion of 3.34 × 10⁵ J/kg.
Model answer
Energy = 0.50 × 3.34 × 10⁵ = 1.67 × 10⁵ J.
- 3
Calculate the energy needed to boil away 0.20 kg of water at 100 °C, given a specific latent heat of vaporisation of 2.26 × 10⁶ J/kg.
Model answer
Energy = 0.20 × 2.26 × 10⁶ = 4.52 × 10⁵ J.
- 4
Melting 2.0 kg of a solid at its melting point requires 6.8 × 10⁵ J. Calculate its specific latent heat of fusion.
Model answer
Specific latent heat = 6.8 × 10⁵ ÷ 2.0 = 3.4 × 10⁵ J/kg.
- 5
A substance has a specific latent heat of 2.0 × 10⁵ J/kg. Calculate the mass changed in state by 5.0 × 10⁴ J.
Model answer
Mass = 5.0 × 10⁴ ÷ (2.0 × 10⁵) = 0.25 kg.
- 6
Explain why no temperature term appears in the equation for the energy needed for a change of state.
Model answer
The temperature stays constant while the state changes, so only the mass and the specific latent heat matter.
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