medium difficulty5 min

Suspensions and Colloids

A suspension is a heterogeneous mixture with large particles that may settle, while a colloid has smaller dispersed particles that do not settle easily and appear fairly uniform.

In one line: Solution stays clear, colloid scatters, suspension settles.

Practice This Concept

Understand it

True solutions, colloids, and suspensions differ mainly in particle size and stability.
Solution particles are very small and do not scatter light clearly.
Colloidal particles are larger than solution particles and can scatter light.
Suspension particles are large enough to be seen or settle on standing.

Rule to remember

Comparison rule: true solution has smallest particles, colloid has intermediate particles, suspension has largest particles.

See it worked out

Follow the example line by line, then use the same method on new questions.

Worked example

1Classify salt water, milk, and chalk powder in water.
2Salt water is a true solution, milk is a colloid, and chalk powder in water is a suspension.

Method you can reuse

1Check whether particles settle.
2Check whether particles can be filtered.
3Check whether light is scattered.
4Use these observations to classify the mixture.

Visual tip

A three-column comparison chart can show particle size, settling, filtration, and Tyndall effect.

Check yourself

Answer the question in your head before opening the answer.

Try it yourself

Why is muddy water called a suspension rather than a true solution?

Think first, then show answer

Muddy water is called a suspension because soil particles are not dissolved uniformly, are large enough to settle, and can often be separated by filtration.

Common wrong answer

Calling milk a suspension.

Why it loses marks: Its particles do not settle quickly like large suspension particles.

Don't mix this up

Students often call colloids true solutions because they look uniform to the naked eye.

Exam tip

Use particle size, settling behaviour, filtration, and light scattering for comparison questions.

Write it in the exam

Each point is worth about one mark. Write point 1 for a 1-mark question and keep adding points as the marks go up.

How CBSE asks it

Students are often asked to compare solution, colloid, and suspension in tabular form.

1
Enough for 1 mark
A suspension is a heterogeneous mixture with large particles that may settle, while a colloid has smaller dispersed particles that do not settle easily and appear fairly uniform.
2
Add for 2 marks
Example: Muddy water is a suspension, milk is a colloid, and salt water is a true solution.
3
Add for 3 marks
True solutions, colloids, and suspensions differ mainly in particle size and stability.

MCQ Quiz

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