Topic 1a - More Separating Techniques

Separating an insoluble solid and a liquid

Filtration is often used if your desired product is an insoluble solid that needs to be separated from a liquid

  1. Fold a piece of filter paper into a cone
  1. Place the filter paper point down into a filter funnel that's sitting in the neck of a container
  1. Pour the mixture into the filter paper
  1. The liquid will pass through the filter paper but the solid won't

Separating a soluble solid and a solution

There are two methods commonly used to remove a soluble product from a solution - evaporation and crystallisation

Evaporation

Really quick way of separating a soluble salt from a solution but you can only use it if the salt doesn't decompose when heated

  1. Pour the solution into an evaporating dish
  1. Place the evaporating dish on top of a tripod and gauze and place a Bunsen burner underneath
  1. Slowly heat the solution. The solvent will evaporate. Eventually the solid will form
  1. Keep heating the evaporation dish until all you have left is a dry solid

Crystallisation

Takes more time but can produce crystals

  1. Place an evaporating dish on top of a tripod with a gauze mat. Place a Bunsen burner underneath
  1. Pour the solution into the evaporating dish and gently heat it
  1. Once some of the solvent has evaporated, or when you see crystals start to form, remove the dish from the heat and leave it to cool
  1. Filter the crystals out of the solution, and leave them in a warm place to dry