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SavannahYear 8
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ScienceMixtures and solutions26 min★★ difficulty

Separating mixtures

Most materials we use are mixtures, and chemists have a toolkit of physical methods to pull them apart without any chemical reaction.

Part of your national curriculum
  • Chemistry: pure and impure substances: Understand the concept of a pure substance and how mixtures can be separated through filtration, distillation and chromatography

Lesson overview

What you'll learn in this lesson

Understand the concept of a pure substance and how mixtures can be separated through filtration, distillation and chromatography

Key learning points

  • • Pure substances and mixtures
  • • Filtration and distillation
  • • Chromatography

This lesson at a glance

  • 26 minutes
  • 14 parts to scroll through
  • 3 quick checks
  • Marked quiz at the end
  • Gentle pace: short sittings with pauses

Words to know

conceptsubstancemixturesseparatedfiltration

Scroll down — the lesson carries on below

Part 1 of 14 · Discover7%
1

Watch & discover

Part 1 of 14

Watch first

Separating mixtures

An English teaching video on this topic from FuseSchool - Global Education. Watch it, then scroll down for the lesson.

In a nutshell

Understand the concept of a pure substance and how mixtures can be separated through filtration, distillation and chromatography

2

Learning cycle

Part 2 of 14

Learning cycle 1 of 2

Part 1 · Pure substances and mixtures

A short piece of teaching, then a check to make sure it has landed.

3

Explore the idea

Part 3 of 14

Learn

Pure substances and mixtures

A pure substance contains only one element or compound throughout, with a fixed, sharp melting and boiling point. A mixture contains two or more substances not chemically combined, so each keeps its own properties and can often be separated by physical methods.

4

Explore the idea

Part 4 of 14

Learn

Filtration and distillation

Filtration separates an insoluble solid from a liquid by passing the mixture through filter paper; the solid is left as a residue. Distillation separates a liquid from a solution by evaporating it, then cooling and condensing the vapour to collect the pure liquid — useful for producing fresh water from salt water.

5

Quick check

Part 5 of 14

Quick check

Which method separates an insoluble solid from a liquid?

6

Reset break

Part 6 of 14

Pause

That's sitting 1 of 2 done

Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.

Stop here for now
7

Quick check

Part 7 of 14

Quick check

How does distillation obtain pure water from salt water?

8

Learning cycle

Part 8 of 14

Learning cycle 2 of 2

Part 2 · Chromatography

A short piece of teaching, then a check to make sure it has landed.

9

Explore the idea

Part 9 of 14

Learn

Chromatography

Chromatography separates substances dissolved in a mixture, such as inks or dyes, based on how strongly each one is attracted to the paper compared to the solvent moving through it. Substances that travel further are generally less strongly attracted to the paper.

10

Quick check

Part 10 of 14

Quick check

What does a pure substance have that a mixture does not?

11

Challenge round

Part 11 of 14

Game · Sort it

Which of these are true?

Drag each card into the right column. Tap a card first if dragging is fiddly.

True

Not true

12

Challenge round

Part 12 of 14

Game · Fill the gaps

Finish the sentences

Choose the word that belongs in each gap.

A pure ____ contains only one element or compound throughout, with a fixed, sharp melting and boiling point.

A mixture contains two or more substances not chemically combined, so each keeps its own properties and can often be ____ by physical methods.

____ separates an insoluble solid from a liquid by passing the mixture through filter paper; the solid is left as a residue.

13

Mastery quiz

Part 13 of 14

Marked quiz

End of lesson quiz: Separating mixtures

3 questions, marked with the reasoning shown. No timer.

  1. 1. Which method separates an insoluble solid from a liquid?

  2. 2. How does distillation obtain pure water from salt water?

  3. 3. What does a pure substance have that a mixture does not?

14

Lesson round-up

Part 14 of 14

Lesson round-up

Ready when you are

Quiz score

Not sat

Games

Not played

Points this lesson

0

Best run

0 in a row

Luna: 0 out of 3 on the practice checks. Only if you feel up to it — one more?

Ask Luna

Do the work

Your written work for this lesson

This is the part you'd do in your book at school. Pick the pieces below, write here or on paper, and photograph anything you draw or work out.

Case study

Why the school greenhouse failed

A science club grew tomato plants in the school greenhouse. In June the plants grew well: leaves were dark green and the fruit set quickly. In July the club went away for two weeks and left the greenhouse door shut. When they came back, the leaves were curled and pale and most of the fruit had dropped.

The club had a data logger inside. It showed the temperature reached 46 °C on several afternoons and the soil moisture fell close to zero. The club knew photosynthesis needs light, water and carbon dioxide, and that enzymes in a plant work best in a narrow range of temperature. Above that range the enzymes stop working properly.

The club repeated the summer with the door propped open and a water bottle drip on each pot. Temperature peaked at 31 °C and the plants survived.

Written for Good Learning Co.

Reading questions

  1. Name the variable the club changed the second time, and one variable they kept the same.
  2. Explain, using the words photosynthesis and enzymes, why the plants were damaged in July.
  3. Write a conclusion for the club's report, saying how far the evidence supports it.

  • Method and results

    Writing

    Write the aim, what you changed, what you measured and what you kept the same, then record your results in a table.

    1 page + results table

  • Conclusion

    Writing

    Explain what your results show and why, using the scientific words from the lesson. Say how you know you can trust them.

    6–8 sentences

  • Labelled diagram

    Diagram

    Draw the apparatus or the process in pencil, label it fully, and photograph it.

    1 labelled diagram

  • Reading and notes

    Reading

    Read the lesson text again and write the key ideas in your own words.

    Half a page of notes

Saved as you type.

Part 1 of 14 · Watch & discover

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    Understand the concept of a pure substance and how mixtures can be separated through filtration, distillation and chromatography

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