the change of state from a solid to a liquid; happens at a fixed temperature for pure substances

the change of state from a liquid to a gas; happens at a fixed temperature for pure substances

the change in energy when 1 kg of a substance changes state

the change in internal energy when the temperature of 1 kg of a substance changes by 1°C

Specific latent heat (E = m l)

Combined science

In the Nuclear physics unit, pupils will build on this knowledge to learn about subatomic particles, unstable nuclei, radioactive decay, ionising radiation and radioactive half-life.

In the Particle explanations of density and pressure unit, pupils learnt how the arrangement and movement of particles in solids, liquids and gases explain density, pressure, floating and convection.

This unit covers energy changes in systems due to heating, forces, and electrical work. It explains reducing energy transfer via insulation, specific heat capacity, and latent heat. Emphasis is on calculations, planning experiments, data interpretation, and evaluating methods.

Energy of moving particles

the change from a solid state to a liquid state

the change from a liquid state to a gas state

the energy transferred when 1 kg of a substance changes state

the change in internal energy when temperature of 1 kg changes by 1°C

Match the following key words or phrases to their definition.

Boiling happens at a specific temperature.

Boiling happens over a range of temperatures.

Freezing and melting happen at different temperatures.

Boiling and condensing happen at the same temperature.

Boiling and melting happen at the same temperature.

Which of the following statements about changes of state for a pure substance at constant pressure are correct?

The average speed of the particles is decreasing.

The fastest particles slow down when they escape.

The fastest particles escape, keeping the average speed the same. 

The particles are gaining mass, so their speed stays the same.

The forces between the particles are increasing.

Why does the temperature stay constant when a substance is boiling as it is heated?

energy = mass × specific heat capacity × temperature change (E = m c Δθ)

energy = mass × specific heat capacity × temperature (E = m c θ)

energy = mass ÷ specific latent heat (E = m ÷ l)

energy = mass × specific latent heat (E = m l)

Which of the following equations, to calculate the energy required to change state, is correct?

The specific latent heat of fusion for ice (melting) is 334 kJ/kg.
Calculate the energy required to melt 600 g of ice.
Give your answer in kJ to 2 significant figures.

The specific latent heat of ice is 334 kJ/kg and its specific heat capacity is 2.11 kJ/kg/°C.
Calculate the energy required to fully melt a 2.0 kg block of ice which starts at a temperature of –20°C.


Which of the following words is used to describe the change of state from a gas to a liquid?

Which of the following changes of state result in an increase in internal energy?

In which state of matter are the electrostatic forces between particles the strongest?

Its temperature increases until it starts to melt.

Changing into the liquid state, its temperature remains constant.

Its temperature increases until it starts to boil.

The temperature of the substance is constant as it changes into its gas state.

A substance is heated continuously from its solid state until it is in its gas state.
Sort the following statements into the correct order to describe how the temperature of the substance changes.

A 100 g sample of pure silver has a melting point of 962°C. What is the melting point of a 50 g sample of the same material?

Calculate the energy needed to heat 8.0 kg of vegetable oil from 20°C to 170°C if the specific heat capacity of the oil is 2000 J/kg/°C.

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