Filtration and Crustallisation

• What is the purpose of filtration in separating mixtures?

  To separate an insoluble solid from a liquid
• When should you use filtration?

  When the solid cannot dissolve in the liquid
• What is the first step in the filtration process?

  Fold filter paper into a cone shape and place it in a funnel
• What happens to the solid during filtration?

  The solid is left on the filter paper as a residue
• What is the process of crystallisation used for?

  • To separate a soluble solid from a solution
  • Involves evaporating the solvent to form crystals
• What is the first step in the crystallisation process?

  Pour the solution into an evaporating dish and gently heat it
• What indicates the point of crystallisation during the process?

  When you see crystals starting to form
• What should you do after removing the dish from heat during crystallisation?

  Leave the solution to cool
• Why do crystals form when the solution cools?

  Because the salt becomes insoluble in the cold, highly concentrated solution
• What is one method to dry the crystals after filtration?

  Leave them in a warm place
• What is a desiccator used for in the drying process?

  To remove water from the surrounding environment
• How do you choose the right purification method for a mixture?

  • Consider the properties of the substances in the mixture
  • Determine if the solid is soluble or insoluble in the liquid
• What purification method would you use to obtain a pure sample of substance X, which is a liquid?

  Simple distillation
• What method would you use to obtain a pure sample of substance Y, which is a solid that dissolves in substance X?

  Crystallisation
• Why is crystallisation preferred over distillation for obtaining substance Y?

  It ensures a pure sample of the solid from the solution