A solute is a substance that has dissolved into a solvent.

A solvent is a liquid into which a solute dissolves.

Occurs when a substance's particles are in the liquid state at its surface with enough energy to change to the gas state and mix with air.

A process that forms solid crystals from a saturated solution by evaporating the solvent.

A crystal is a solid whose particles are arranged in a highly ordered, repeating pattern.

Separating a soluble solid from a liquid

Science

Separating an insoluble solid from a liquid

Separating pure salt from dirty rock salt

Separating liquids

Simple distillation

Distillation: practical

Chromatography

In the Understanding Chemical Reactions unit, pupils will build on their understanding of physical changes to learn how atoms rearrange to form new substances during chemical reactions (chemical changes).

In the key stage 2 Properties, changes and separating materials unit, pupils learnt about mixtures, including solutions, and separation techniques including filtering and evaporation.

This unit covers techniques for separating mixtures, including filtration, evaporation, distillation, and chromatography, as well as identifying pure substances. Conduct experiments safely, record observations, evaluate methods, and suggest improvements.

Separation techniques

Physical activity and equipment requiring safe use

A substance that has dissolved into a solvent.

A solid whose particles are arranged in an irregular pattern.

Dissolving is a {{}} process as solute can be added to the solvent and the solvent can then be evaporated to recover the solute.

Forms solid crystals from a saturated solution.

Change from the liquid state to the gas state occurring at the boiling point.

Change from the liquid state to the gas state occurring below the boiling point.

Forms solid crystals from a dilute solution.

Which definition best describes evaporation?

What happens to the size of crystals formed during crystallisation if the solvent evaporates slowly?

What is the name of the process that forms solid crystals from a saturated solution by evaporating the solvent?

Solvents evaporate into the air during crystallisation. How does heating affect this process?

What process happens when a solid can be observed to 'disappear' in a liquid to make a solution?

When a process is able to go backwards, or be "undone", it is said to be {{}}.

The mixture formed when a solid dissolves in a liquid

Put the following changes of state for ice/water in order starting from the one that requires the lowest temperature to the one that requires the highest temperature.

A volume of salt solution containing 0.5 g of salt was placed in a beaker and left for 2 weeks on the windowsill, after which only crystals of salt remained. How much salt would be present?

No change as the sugar would still be dissolved.

No change as temperature does not affect the solubility of the sugar.

Solid sugar would start to form as the water would evaporate.

Solid sugar would start to form as it is less soluble at a lower temperature.

Sugar was added to water at 60℃ until no more sugar could dissolve. The solution was left to cool. What would you expect to see and why?

Separating a soluble solid from a liquid

Lesson outcome

Content guidance