Solution vs Suspension — Difference (with Table & FAQs)
Solution vs Suspension compared side by side — a 6-row comparison table, 4 key points and 7 exam FAQs. Class 9-10 Chemistry, free and no sign-up.
TL;DR: Solution vs Suspension compared side by side — a 6-row comparison table, 4 key points and 7 exam FAQs. Class 9-10 Chemistry, free and no sign-up.
Written & reviewed by the Syllab.in Academic Team (CBSE/NCERT subject experts) · Updated
The main difference between Solution and Suspension: A solution is a homogeneous mixture where solute dissolves completely in the solvent at the molecular level, forming a single phase. A suspension is a hete
Solution vs Suspension — Comparison Table
| Basis | Solution | Suspension |
|---|---|---|
| Homogeneity | Homogeneous mixture throughout | Heterogeneous mixture with visible particles |
| Transparency | Transparent or translucent | Opaque appearance |
| Particle Size | Molecular or ionic level (smaller than 1 nm) | Larger particles visible to naked eye |
| Settling | Does not settle over time | Particles settle at the bottom |
| Filtering | Cannot be separated by filtration | Can be separated by filtration |
| Example | Salt water, sugar solution, salt in vinegar | Muddy water, chalk in water, milk of magnesia |
Key Points
- Solutions are formed when solute dissolves at molecular level
- Suspensions involve physical dispersion without chemical dissolution
- Solute in a solution cannot be recovered by simple filtration
- Suspended particles in a suspension can be recovered by filtration
Solution — a true, homogeneous mixture
A solution is a homogeneous mixture of two or more substances, meaning its composition is exactly the same throughout. The dissolved substance is the solute and the one doing the dissolving is the solvent; in salt water, salt is the solute and water the solvent.
The solute particles are extremely small — less than 1 nanometre across — so they are invisible even under a microscope, they pass straight through filter paper, they never settle on standing, and they do not scatter a beam of light. A solution is therefore transparent and stable.
Suspension — a heterogeneous mixture that settles
A suspension is a heterogeneous mixture in which solid particles are dispersed through a liquid without dissolving. The particles are large, greater than about 100 nanometres, and are big enough to be seen with the naked eye or a simple microscope.
Because the particles are so large, a suspension behaves in the opposite way to a solution at every point: it is unstable and settles out when left undisturbed, the particles are held back by filter paper, and it scatters light strongly. Muddy water left in a glass overnight shows all of this.
The third type: colloids
Between the two sits the colloid, and leaving it out costs marks. A colloid has particle sizes between roughly 1 and 1000 nanometres — larger than in a solution but smaller than in a suspension.
A colloid appears homogeneous to the eye but is actually heterogeneous. Its particles are too small to settle out and too small to be stopped by ordinary filter paper, yet large enough to scatter light. Milk, fog, smoke, ink and jelly are all colloids. Separating a colloid needs centrifugation, since filtration will not do it.
The Tyndall effect — the test that tells them apart
The Tyndall effect is the scattering of a beam of light by particles in a mixture, which makes the path of the beam visible. It is the standard laboratory test in this chapter.
A true solution does NOT show the Tyndall effect — its particles are too small to scatter light, so the beam passes through invisibly. Colloids and suspensions both DO show it. This is why sunbeams are visible streaming through a dusty room or through fog, and why a torch beam is visible in milk but not in salt water.
The full comparison
Learn these five properties as a set; questions almost always ask for a table.
- Nature — solution: homogeneous. Suspension: heterogeneous. Colloid: appears homogeneous but is heterogeneous.
- Particle size — solution: less than 1 nm. Colloid: 1–1000 nm. Suspension: more than 100 nm and usually visible.
- Stability — solution: stable, never settles. Colloid: stable, does not settle. Suspension: unstable, settles on standing.
- Filtration — solution and colloid particles pass through filter paper. Suspension particles do not.
- Tyndall effect — solution: absent. Colloid and suspension: present.
Solution vs Suspension — Worked Examples
- Salt dissolved in water — A solution. Transparent, stable, passes through filter paper and shows no Tyndall effect.
- Chalk powder stirred into water — A suspension. The particles are visible, settle at the bottom and are caught by filter paper.
- Milk — A colloid. It looks uniform but scatters light, and its fat droplets cannot be filtered out.
- A torch beam visible in fog but not in clear air — The Tyndall effect. Fog is a colloid whose droplets scatter the light; the gases of clear air do not.
Common Mistakes Students Make
- Forgetting colloids as the third category. Almost every full-mark answer needs all three.
- Saying a solution shows the Tyndall effect. It does not — that is precisely what distinguishes it from a colloid.
- Claiming a colloid settles on standing. It does not; only a suspension does.
- Thinking a colloid can be separated by ordinary filtration. It needs centrifugation.
- Calling milk a solution because it looks uniform. Appearance is not the test — the Tyndall effect is.
Diagrams
Where This Shows Up in Real Life
Why medicine bottles say "shake well before use"
Many liquid medicines are suspensions: the active drug is not dissolved but dispersed as fine solid particles. Left standing, those particles settle to the bottom, so the first dose poured would be weak and the last dangerously strong. Shaking redistributes them evenly. A syrup that is a true solution — glucose in water, say — needs no such instruction, because dissolved particles never settle. The label tells you which type you are holding.
How water is purified at a treatment plant
Muddy river water is a suspension, and its large particles settle under gravity — the sedimentation step. Alum is added to make the finer colloidal particles clump into larger ones heavy enough to settle, a process called coagulation or flocculation. Filtration then removes what remains suspended. Note that no amount of filtering removes dissolved salts, because a true solution passes straight through filter paper; that needs distillation or reverse osmosis.
The Tyndall effect in daily life
Sunlight streaming through a gap in a forest canopy becomes visible because mist droplets scatter it. So do the beams of car headlights in fog, and a torch shone through milk. In each case a colloid is scattering the light. Shine the same torch through clear salt water and the beam is invisible, because a true solution’s particles are far too small to scatter. It is the simplest test that distinguishes the three mixture types.
Why the sky is blue
The atmosphere scatters shorter blue wavelengths more strongly than longer red ones, which is why the daytime sky is blue and why the sun looks red at sunrise and sunset, when its light travels through much more atmosphere and the blue has been scattered away. This is scattering by very fine particles and molecules — the same physical principle underlying the Tyndall effect you test in the laboratory.
Board-Style Questions with Model Answers
Distinguish between a true solution, a colloid and a suspension on the basis of particle size, appearance, stability, filterability and the Tyndall effect. (5 marks)
A true solution has particles smaller than 1 nanometre. It is homogeneous and transparent, completely stable so the particles never settle, passes unchanged through filter paper, and does NOT show the Tyndall effect because its particles are too small to scatter light. A colloid has particles between 1 and 1000 nanometres. It appears homogeneous to the naked eye but is actually heterogeneous, is stable so it does not settle on standing, passes through ordinary filter paper but can be separated by centrifugation, and DOES show the Tyndall effect. A suspension has particles larger than about 100 nanometres, often visible to the naked eye. It is heterogeneous, unstable so the particles settle out on standing, is retained by filter paper, and also shows the Tyndall effect. Examples are salt water, milk and muddy water respectively.
What is the Tyndall effect? Describe an experiment to demonstrate it. (3 marks)
The Tyndall effect is the scattering of a beam of light by the particles of a colloid or suspension, which makes the path of the beam visible. To demonstrate it, take two beakers, one containing a true solution such as common salt in water and the other containing a colloid such as dilute milk or a starch solution. Place each in a dark room and shine a narrow beam of light from a torch through it, viewing at right angles to the beam. In the salt solution the beam is invisible, because the dissolved particles are smaller than 1 nanometre and cannot scatter light. In the milk the path of the beam is clearly visible as a bright track, because the colloidal particles are large enough to scatter it. The same effect is seen when sunlight enters a dusty room or passes through a forest canopy.
Why must a suspension be shaken before use, but a solution need not be? (2 marks)
A suspension is a heterogeneous mixture whose particles are large and dense enough for gravity to pull them down, so on standing they settle at the bottom and the mixture becomes non-uniform. Shaking redistributes the particles so that each portion poured contains the intended amount. A true solution is homogeneous, with particles smaller than 1 nanometre that remain permanently dispersed among the solvent molecules and never settle, so its composition is identical throughout at all times and no shaking is required.
Classify the following as solution, colloid or suspension: salt water, milk, muddy water, soda water, fog, chalk powder in water. (3 marks)
Salt water is a true solution, because the sodium chloride dissolves completely into particles smaller than 1 nanometre. Milk is a colloid, an emulsion of liquid fat droplets dispersed in water, which is why it appears uniform but shows the Tyndall effect. Muddy water is a suspension, since the soil particles are large, visible and settle on standing. Soda water is a solution of carbon dioxide gas in water. Fog is a colloid, consisting of tiny liquid water droplets dispersed in air, an aerosol. Chalk powder in water is a suspension, because the chalk does not dissolve and settles out.
How can the components of a suspension and of a colloid be separated? (2 marks)
A suspension can be separated by ordinary filtration, because its particles are larger than the pores of filter paper and are therefore retained on it; simply allowing it to stand so the particles sediment will also partly separate it. A colloid cannot be separated by filtration, since its particles are small enough to pass through filter paper. It is separated by centrifugation, in which rapid spinning generates a force much larger than gravity and drives the dispersed particles to the bottom of the tube. Coagulation, for example by adding alum, can also make colloidal particles clump together until they are large enough to settle.
Assertion–Reason Questions (CBSE Format)
For each question choose: (a) both A and R are true and R is the correct explanation of A; (b) both are true but R is not the correct explanation; (c) A is true but R is false; (d) A is false but R is true.
1. Assertion (A): A true solution does not show the Tyndall effect.
Reason (R): Its particles are smaller than 1 nm and cannot scatter light.
Answer: (a) — Both are true and the reason explains the assertion. Scattering requires particles comparable to the wavelength of light; solute particles are far too small.
2. Assertion (A): Milk is a true solution because it looks uniform.
Reason (R): A mixture that appears uniform to the eye is homogeneous.
Answer: (d) — The assertion is false — milk is a colloid, which is why it scatters light. The reason is also false as a general rule: appearance is not the test, since colloids look uniform while being heterogeneous.
3. Assertion (A): Colloidal particles cannot be separated by filtration.
Reason (R): Colloidal particles are smaller than the pores of filter paper.
Answer: (a) — Both are true and correctly linked. This is why centrifugation, not filtration, is used to separate a colloid.
4. Assertion (A): Muddy water becomes clear on standing.
Reason (R): Suspensions are unstable and their particles settle under gravity.
Answer: (a) — Both are true and the reason explains the assertion. This sedimentation is the first step in water treatment.
Quick Self-Check
Q1. Which of these does NOT show the Tyndall effect?
- A. Milk
- B. Fog
- C. Salt solution
- D. Muddy water
Answer: C. Salt solution — A true solution has particles smaller than 1 nm, too small to scatter light. Colloids and suspensions both scatter it.
Q2. Particles of a suspension:
- A. Pass through filter paper
- B. Never settle down
- C. Are smaller than 1 nm
- D. Settle down on standing
Answer: D. Settle down on standing — Suspension particles are large and heavy enough to settle under gravity when left undisturbed — the mixture is unstable.
Q3. Milk is an example of a:
- A. Solution
- B. Suspension
- C. Colloid
- D. Pure substance
Answer: C. Colloid — Milk's fat droplets are between 1 and 1000 nm, so it appears uniform, does not settle, but does scatter light.
Q4. A colloid can be separated by:
- A. Filtration
- B. Centrifugation
- C. Evaporation only
- D. It cannot be separated
Answer: B. Centrifugation — Colloidal particles pass through filter paper, so centrifugation is used to spin them out instead.
Key Terms Glossary
- Solution
- A homogeneous mixture with particles smaller than 1 nm. Stable, transparent, no Tyndall effect.
- Colloid
- A heterogeneous mixture with particles 1-1000 nm that LOOKS homogeneous. Stable, shows the Tyndall effect.
- Suspension
- A heterogeneous mixture with particles above ~100 nm. Unstable, settles on standing, retained by filter paper.
- Tyndall effect
- The scattering of a light beam by colloid or suspension particles, making the beam path visible.
- Homogeneous
- Uniform in composition throughout, with no visible boundary between components.
- Heterogeneous
- Not uniform — the components remain physically distinct.
- Dispersed phase
- The substance spread through a colloid, e.g. fat droplets in milk.
- Dispersion medium
- The substance a colloid is dispersed in, e.g. water in milk.
- Emulsion
- A colloid of one liquid dispersed in another, such as milk.
- Aerosol
- A colloid of solid or liquid particles dispersed in a gas, such as fog or smoke.
- Centrifugation
- Rapid spinning used to separate a colloid, since filtration cannot.
- Coagulation
- Making colloidal particles clump together until heavy enough to settle, e.g. adding alum to water.
One-Minute Revision
- THREE types, not two: SOLUTION (<1 nm), COLLOID (1-1000 nm), SUSPENSION (>100 nm).
- Tyndall effect: solution NO, colloid YES, suspension YES. It is the quickest test.
- Settles on standing: only the SUSPENSION. Solutions and colloids do not.
- Filter paper stops only the SUSPENSION. Colloids need CENTRIFUGATION.
- A colloid LOOKS homogeneous but IS heterogeneous. Appearance is not the test.
- Milk, fog, smoke, ink, jelly = colloids. Muddy water, chalk in water = suspensions.
- Salt water and soda water = true solutions. Filtration will never remove dissolved salt.
- Alum coagulates colloidal particles so they clump and settle — the water-treatment step.
Syllabus reference: NCERT Class 9 Science, Chapter 2 — Is Matter Around Us Pure?
Frequently Asked Questions
What is the difference between a solution and a suspension?
In a solution the solute particles are so small they dissolve completely and cannot be seen or filtered out (e.g. salt in water). In a suspension the particles are large, visible, settle down on standing and can be filtered out (e.g. sand in water).
Is a solution transparent or cloudy?
A true solution is transparent — light passes straight through it. A suspension is usually cloudy or opaque.
Can a suspension be separated by filtration?
Yes. The large particles of a suspension can be separated by filtration, while the dissolved particles of a solution cannot.
What is the main difference between a solution and a suspension?
A solution is a homogeneous mixture with particles smaller than 1 nm that never settle, pass through filter paper and do not scatter light. A suspension is heterogeneous, with particles larger than about 100 nm that settle on standing, are held back by filter paper and scatter light strongly.
What is the Tyndall effect and why does it matter?
It is the scattering of a beam of light by the particles of a mixture, which makes the beam's path visible. It matters because it is the simplest laboratory test to distinguish a true solution, which shows no Tyndall effect, from a colloid or suspension, which both do.
Is a colloid homogeneous or heterogeneous?
A colloid is heterogeneous in nature, even though it appears homogeneous to the naked eye. Its dispersed particles are distinct from the medium they are spread through, which is why it scatters light — but they are too small to be seen or to settle.
Why does muddy water become clear on standing?
Muddy water is a suspension. Its soil particles are large and dense enough that gravity pulls them to the bottom once the water is left undisturbed, leaving clearer water above. A solution would never separate this way.