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
- 17 parts to scroll through
- 3 quick checks
- Marked quiz at the end
- Gentle pace: short sittings with pauses
Words to know
Scroll down — the lesson carries on below
Watch & discover
Part 1 of 17
Visual introductionPicture this
Separating mixtures
Most materials we use are mixtures, and chemists have a toolkit of physical methods to pull them apart without any chemical reaction.
In a nutshell
Understand the concept of a pure substance and how mixtures can be separated through filtration, distillation and chromatography
Learning cycle
Part 2 of 17
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.
Explore the idea
Part 3 of 17
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.
Reset break
Part 4 of 17
Pause
That's sitting 1 of 4 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.
Explore the idea
Part 5 of 17
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.
Quick check
Part 6 of 17
Quick check
Part 7 of 17
Reset break
Part 8 of 17
Pause
That's sitting 2 of 4 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.
Learning cycle
Part 9 of 17
Learning cycle 2 of 2
Part 2 · Chromatography
A short piece of teaching, then a check to make sure it has landed.
Explore the idea
Part 10 of 17
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.
Quick check
Part 11 of 17
Reset break
Part 12 of 17
Pause
That's sitting 3 of 4 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.
Challenge round
Part 13 of 17
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
Challenge round
Part 14 of 17
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.
Challenge round
Part 15 of 17
Game · Recall cards
Which method separates an insoluble solid from a liquid?
Card 1 of 4
Mastery quiz
Part 16 of 17
Marked quiz
End of lesson quiz: Separating mixtures
4 questions, marked with the reasoning shown. No timer.
1. Which method separates an insoluble solid from a liquid?
2. How does distillation obtain pure water from salt water?
3. What does a pure substance have that a mixture does not?
4. A pure substance melts
Lesson round-up
Part 17 of 17
Lesson round-up
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Understand the concept of a pure substance and how mixtures can be separated through filtration, distillation and chromatography