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Year 7

Separating liquids

I can describe how a mixture of two liquids can be separated from each other.

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New
New
Year 7

Separating liquids

I can describe how a mixture of two liquids can be separated from each other.

Download all resources
Share activities with pupils

Lesson details

Key learning points

  1. Immiscible liquids do not mix and if allowed to settle, one will float above the other.
  2. Immiscible liquids can be separated by decanting or using a separating funnel.
  3. If left, miscible liquids do not separate into layers.
  4. The boiling points of liquids can be used to separate miscible liquids by changing states.

Common misconception

If a substance cannot be seen, it has disappeared and is no longer present.

Remind pupils of work regarding evaporation and use particle models to describe / explain what a solution of two liquids is like.

Keywords

  • Density - Density is a measurement of mass per unit volume; how tightly packed a substance's particles are in a particular space.

  • Boiling point - The boiling point of a substance is the temperature at which it changes from a liquid state to a gas state.

  • Immiscible - Liquids that are not soluble in another liquid are described as immiscible in that liquid.

  • Miscible - Liquids that dissolve in another liquid are described as miscible in that liquid.

  • Decanting - Decanting is a process of pouring off the top layer in a mixture of immiscible liquids, or a liquid and insoluble solid.

Challenge pupils to decant a small sample of oil & water mixture (perhaps link to using juices from roast to make gravy) and compare ease of separation by demonstrating use of a separation funnel.
Teacher tip

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).

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Starter quiz

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6 Questions

Q1.
True or false? Solids that do not dissolve in a liquid are called insoluble.
Correct answer: True
False
Q2.
What is the process of changing a liquid into a vapour (gas) called?
Correct Answer: evaporation, evaporating, boiling
Q3.
True or false? When a solution is heated, the solvent evaporates more slowly.
True
Correct answer: False
Q4.
Which properties below would be helpful in separating a mixture of substances?
Smell of the substances.
Correct answer: Boiling points of the substances.
Colour of the substances.
Correct answer: Solubility of the substances.
Q5.
True or false? All liquids have the same boiling point of 100℃.
True
Correct answer: False
Q6.
In a mixture of two liquids with very different densities, the less dense liquid will ...
Correct answer: float on top
sink to the bottom
mix with the other liquid

Exit quiz

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6 Questions

Q1.
What is the main purpose of using a 'separating funnel' in the lab?
To measure the volume of a liquid.
To heat substances.
To mix two liquids.
Correct answer: To separate immiscible liquids.
Q2.
True or false? Decanting is effective for separating liquids with similar densities.
True
Correct answer: False
Q3.
If two liquids can mix completely together to form one layer, they are said to be ...
Correct Answer: miscible
Q4.
True or false? A separating funnel can be used to separate two liquids that are miscible.
True
Correct answer: False
Q5.
Match the keywords with their correct definition.
Correct Answer:density,Measurement of mass per unit volume.

Measurement of mass per unit volume.

Correct Answer:immiscible,Liquids that are not soluble in another liquid.

Liquids that are not soluble in another liquid.

Correct Answer:miscible,Liquids that dissolve in another liquid.

Liquids that dissolve in another liquid.

Correct Answer:decanting,Process of pouring off the top layer in a mixture of liquids

Process of pouring off the top layer in a mixture of liquids

Correct Answer:solution,A mixture comprised of a solute dissolved in a solvent.

A mixture comprised of a solute dissolved in a solvent.

Q6.
Which of the following techniques should be used to separate miscible liquids?
Filtering, to collect the solute.
Correct answer: Heating, as the liquids have different boiling points.
Decanting, to separate the layers.