New
New
Year 5

Removing salt from seawater (non-statutory)

I can investigate ways of making seawater safe to drink.

New
New
Year 5

Removing salt from seawater (non-statutory)

I can investigate ways of making seawater safe to drink.

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Lesson details

Key learning points

  1. The water in our seas and oceans contains salt. This water is not safe for drinking.
  2. Evaporation can be used to remove the water from a salt solution.
  3. Condensation is when a water in the gas state (water vapour) is cooled so that it changes to water in the liquid state.
  4. Scientists and engineers investigate ways of making seawater safe to drink using evaporation and condensation.
  5. Microorganisms must also be removed from water to make it safe to drink.

Keywords

  • Seawater - Seawater is water from a sea or ocean.

  • Solution - Some solids dissolve in liquids to form a solution.

  • Evaporation - Evaporation is the change of state from a liquid to a gas.

  • Condensation - Condensation is the change of state from a gas to a liquid.

  • Desalination - Desalination is the process of removing salt from seawater.

Common misconception

Saltwater is safe to drink.

Teaching slides will explain that drinking saltwater can make us ill and will explain the process of desalination.

Use the guidance in the additional materials document to create a model 'solar still' before the lesson or build as it is explained in the explanation slides, for whole class observations.
Teacher tip

Equipment

Desk lamp, large bowl, small bowl / ramekin, recycled plastic bag, elastic band, 200 ml salt solution, 5 coins or other weight.

Content guidance

  • Risk assessment required - equipment

Supervision

Adult supervision required

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Lesson video

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6 Questions

Q1.
A solid which is soluble in water will in water.
Correct Answer: dissolve
Q2.
Which of these materials are soluble in water?
Correct answer: sugar
Correct answer: salt
sand
soil
Q3.
Match the temperatures of water with its state: solid, liquid or gas.
An image in a quiz
Correct Answer:below 0°C,solid

solid

Correct Answer:between 0°C and 100°C,liquid

liquid

Correct Answer:above 100°C,gas

gas

Q4.
What is water called in its gas state?
ice vapour
water gas
Correct answer: water vapour
smoke
Q5.
When a solution is heated using an oil burner, what process takes place?
An image in a quiz
Correct answer: evaporation
condensation
melting
Q6.
If you carried out evaporation on a salt solution, what would be left behind?
Correct answer: salt
water
a salt solution
salty water

6 Questions

Q1.
True or false? The water in our seas and oceans contains salt.
Correct answer: true
false
Q2.
What process can we use to remove the water from a salt solution?
freezing
melting
Correct answer: evaporation
dissolving
Q3.
What is the name of water in the gas state?
Correct Answer: water vapour, Water vapour
Q4.
Condensation is when water in the gas state is so that it changes to water in the liquid state.
heated
Correct answer: cooled
dissolved
melted
Q5.
Scientists and engineers investigate ways of making seawater safe to drink using...
Correct answer: evaporation and condensation.
soluble and insoluble.
grouping and classifying.
melting and freezing.
Q6.
Which of these are tiny living things that must be removed from water to make it safe to drink?
microscopes
microwaves
Correct answer: microorganisms

Additional material

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