Chapter 2: Is Matter Around Us Pure?

What is a Solution?

Solutions 💧

A solution is a homogeneous mixture of two or more substances.

Components of a Solution

ComponentDescription
SolventDissolves other components (usually larger amount)
SoluteGets dissolved in solvent (usually smaller amount)

Types of Solutions

Solution TypeSoluteSolventExample
Solid in LiquidSugarWaterSugar water
Liquid in LiquidIodineAlcoholTincture of iodine
Gas in LiquidCO₂WaterSoda water
Gas in GasO₂, N₂—Air

🌬️ Air Composition

  • Nitrogen: 78%
  • Oxygen: 21%
  • Other gases: 1%

Properties of a Solution

✅ Homogeneous — same throughout ✅ Particle size — < 1 nanometre ✅ No scattering — light passes through clearly ✅ Stable — particles do not settle ✅ Cannot be filtered — too small

🏭 Alloys — Solid Solutions!

Alloys are mixtures of:

  • Two or more metals, OR
  • A metal and a non-metal

Example: Brass = 30% Zinc + 70% Copper

Alloys are considered mixtures because:

  1. They have variable composition
  2. They show properties of constituents