Chemistry: Mixtures
Pure & Impure Matter Around Us (Class 9–12)
What's inside this booklet?
Pure substances vs mixtures • Solutions, suspensions, colloids • Tyndall effect •
Separation techniques • Solubility & Colligative properties • Comprehensive Question
Bank (MCQs, A-R, Q&A).
1. Matter — A Quick Recap
Matter is anything that has mass and occupies space. Chemists classify matter by its
composition into pure substances and mixtures.
Classification of Matter
Matter
↓
Pure Mixtures
Substances
Elements / Homo- /
CompoundsHeterogeneous
Page 1
, 2. Pure Substances vs Mixtures
Property Pure Substance Mixture
Composition Fixed Variable
Components Single element/compound Two or more physically combined
Properties Definite (sharp m.p./b.p.) Intermediate; not sharp
Separation Chemical only Physical (filtration, etc.)
Key Concept: A compound (like H₂O) has properties completely different from its
constituent elements, whereas a mixture (like air) retains the properties of its
components.
3. Solutions, Suspensions, and Colloids
Solutions are homogeneous, while suspensions and colloids are heterogeneous. The
primary difference lies in the size of the particles.
Property True Solution Colloid Suspension
Particle Size < 1 nm 1–1000 nm > 1000 nm
Tyndall Effect Absent Present Visible (initially)
Stability Very Stable Stable Unstable (settles)
Example Salt in water Milk, Fog Chalk in water
Tyndall Effect
The scattering of a beam of light by colloidal particles, making the path of light
visible. This is why you can see sunbeams through trees in a misty forest.
Page 2
Pure & Impure Matter Around Us (Class 9–12)
What's inside this booklet?
Pure substances vs mixtures • Solutions, suspensions, colloids • Tyndall effect •
Separation techniques • Solubility & Colligative properties • Comprehensive Question
Bank (MCQs, A-R, Q&A).
1. Matter — A Quick Recap
Matter is anything that has mass and occupies space. Chemists classify matter by its
composition into pure substances and mixtures.
Classification of Matter
Matter
↓
Pure Mixtures
Substances
Elements / Homo- /
CompoundsHeterogeneous
Page 1
, 2. Pure Substances vs Mixtures
Property Pure Substance Mixture
Composition Fixed Variable
Components Single element/compound Two or more physically combined
Properties Definite (sharp m.p./b.p.) Intermediate; not sharp
Separation Chemical only Physical (filtration, etc.)
Key Concept: A compound (like H₂O) has properties completely different from its
constituent elements, whereas a mixture (like air) retains the properties of its
components.
3. Solutions, Suspensions, and Colloids
Solutions are homogeneous, while suspensions and colloids are heterogeneous. The
primary difference lies in the size of the particles.
Property True Solution Colloid Suspension
Particle Size < 1 nm 1–1000 nm > 1000 nm
Tyndall Effect Absent Present Visible (initially)
Stability Very Stable Stable Unstable (settles)
Example Salt in water Milk, Fog Chalk in water
Tyndall Effect
The scattering of a beam of light by colloidal particles, making the path of light
visible. This is why you can see sunbeams through trees in a misty forest.
Page 2
