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Chapter 1: Exploring Mixtures
and Their Separation
Grade 9 Chemistry (Detailed PPT)
Introduction to Matter
• Matter is anything that has mass and occupies
space
• All substances around us are matter
• Matter can be pure substances or mixtures
What is a Mixture?
• Combination of two or more substances
• No chemical reaction between components
• Components retain individual properties
• Can be separated by physical methods
Types of Mixtures
• Homogeneous mixtures: uniform composition
• Heterogeneous mixtures: non-uniform
composition
• Examples help identify the type
Homogeneous Mixtures
• Same composition throughout
• Single phase visible
• Example: salt solution, air
Heterogeneous Mixtures
• Different composition in different parts
• Multiple phases visible
• Example: sand and water
Solutions
• Homogeneous mixture of solute and solvent
• Solute: substance dissolved
• Solvent: medium that dissolves solute
Properties of Solutions
• Uniform composition
• Particles are very small
• Do not scatter light
• Cannot be separated by filtration
Concentration of Solution
• Amount of solute in given solvent
• Can be dilute or concentrated
• Measured in different units
Suspensions
• Heterogeneous mixture
• Particles are large and visible
• Particles settle down on standing
• Can be filtered
Properties of Suspensions
• Non-uniform
• Scatter light
• Unstable (settle down)
Colloids
• Intermediate between solution and
suspension
• Particles do not settle
• Example: milk, fog
Properties of Colloids
• Show Tyndall effect
• Particles not visible to naked eye
• Stable mixture
Separation of Mixtures
• Based on physical properties
• Size, density, solubility, boiling point
Filtration
• Separates insoluble solids from liquids
• Uses filter paper
• Example: tea filtration
Evaporation
• Separates dissolved solids from liquids
• Liquid evaporates leaving solid behind
• Example: salt from seawater
Decantation
• Liquid poured off without disturbing sediment
• Used for solid-liquid or liquid-liquid separation
Distillation
• Based on difference in boiling points
• Used to separate liquids
• Example: purified water
Chromatography
• Separates components based on movement
• Used for dyes, inks
Applications
• Used in industries
• Water purification
• Food processing
Summary
• Mixtures are combinations of substances
• Different types exist
• Various methods used for separation