Introduction

Matter is anything that occupies space and has mass. It exists in different forms such as solids, liquids, and gases, made up of tiny particles called atoms or molecules. In our surroundings, matter may be found in a pure form or as a mixture of different substances.

Pure Substances and Mixtures

A pure substance consists of only one kind of particle and has a uniform composition throughout. Its properties, such as melting point, boiling point, density, and color, remain the same regardless of where it is obtained from.

Examples of Pure Substances:

• Sodium chloride (NaCl) – common salt
• Sugar (C₁₂H₂₂O₁₁) – same composition everywhere
• Distilled water (H₂O) – free from dissolved salts and impurities

A mixture, on the other hand, contains two or more pure substances physically combined in any proportion. Mixtures retain the properties of their components and can be separated by physical methods like filtration, evaporation, or distillation.

Examples from Daily Life

• Mixtures: Air, soft drinks, soil, milk
• Pure Substances: Iron, oxygen gas, pure gold, diamond

Separation of Mixtures

The components of a mixture can be separated using simple physical processes:

• Evaporation: Used to separate salt from seawater.
• Filtration: Removes insoluble solids from liquids.
• Distillation: Separates liquids with different boiling points.

Why Pure Substances are Important

Pure substances are essential in chemistry, medicine, and industry because they have predictable and reliable properties. For example:

• In medicine, drugs must be pure to be effective and safe.
• In laboratories, reactions require pure chemicals for accurate results.

Key Difference Between Pure Substances and Mixtures

Quick Recap for Exams

• Matter is made up of particles.
• Pure substances have uniform composition and properties.
• Mixtures are combinations of pure substances in any proportion.
• Mixtures can be homogeneous (uniform) or heterogeneous (non-uniform).