Diffusion, solutions and solubility
Sugar seems to vanish into tea — but it hasn't gone anywhere, it has just spread out between the water particles.
Part of your national curriculum
- Chemistry: pure and impure substances: Understand diffusion in terms of the particle model, and the concepts of solutions, solvents, solutes and solubility
Lesson overview
What you'll learn in this lesson
Understand diffusion in terms of the particle model, and the concepts of solutions, solvents, solutes and solubility
Key learning points
- • Diffusion
- • Solutions: solute, solvent, solution
- • Solubility
This lesson at a glance
- 24 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
Diffusion, solutions and solubility
Sugar seems to vanish into tea — but it hasn't gone anywhere, it has just spread out between the water particles.
In a nutshell
Understand diffusion in terms of the particle model, and the concepts of solutions, solvents, solutes and solubility
Learning cycle
Part 2 of 17
Learning cycle 1 of 2
Part 1 · Diffusion
A short piece of teaching, then a check to make sure it has landed.
Explore the idea
Part 3 of 17
Learn
Diffusion
Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration, caused by the particles' own random motion. It happens fastest in gases, more slowly in liquids, and is essentially impossible in most solids.
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
Solutions: solute, solvent, solution
When a solute (the substance that dissolves, e.g. sugar) mixes completely with a solvent (the substance doing the dissolving, e.g. water), the result is a solution. The solute particles spread evenly among the solvent particles — nothing is lost, just spread out.
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 · Solubility
A short piece of teaching, then a check to make sure it has landed.
Explore the idea
Part 10 of 17
Learn
Solubility
Solubility describes how much solute can dissolve in a given amount of solvent at a certain temperature. Most solids become more soluble as temperature increases, which is why sugar dissolves faster and more completely in hot tea than in cold water.
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.
____ is the net movement of particles from an area of higher concentration to an area of lower concentration, caused by the particles' own random motion.
Challenge round
Part 15 of 17
Game · Recall cards
What causes diffusion?
Card 1 of 4
Mastery quiz
Part 16 of 17
Marked quiz
End of lesson quiz: Diffusion, solutions and solubility
4 questions, marked with the reasoning shown. No timer.
1. What causes diffusion?
2. In a solution of salt water, what is the solute?
3. What generally happens to the solubility of a solid as temperature rises?
4. Diffusion is fastest in
Lesson round-up
Part 17 of 17
Lesson round-up
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Understand diffusion in terms of the particle model, and the concepts of solutions, solvents, solutes and solubility