Mixtures

• Pure substances and mixtures

  • Pure substance consist of one element or compound only
  • a mixture consists of two or more substances, not chemically joined together
• Mixture

  • Two or more substances that are not joined together
  • the substances can be elements, compounds, or both
• Filtration

  • Filtration separates and insoluble solid from a liquid
  • filtration works as filter paper has tiny holes in it:
  • dissolved solids and solvent molecules go through the holes
  • pieces of undiscovered solid do not go through the holes
• Crystallisation

  • Makes solid crystals from a solution
  • On warming a solution for crystallisation:
  • -the solvent evaporates
  • -crystals form in the evaporating basin
• Simple distillation

  • Simple distillation separates a solvent from a solution
  • simple distillation is useful for obtaining pure water from seawater
  • Simple distillation works because the dissolved solute has a much higher boiling point than the solvent
• Simple distillation

  • Salty water is heated and water evaporates
  • The water vapour cools in the condenser and drips into the beaker
• Fractional distillation

  • a mixture of several substances such as crude oil,is distilled and the evaporated components are collected as they condense at different temperatures
• Chromatography

  • Separated mixtures of soluble substances
  • it has 2 phases: 1-the mobile phase that moves through paper 2-the stationary phase
  • Paper chromatography is useful for distinguishing pure and impure substances and identifying substances