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
- Fold a piece of filter paper into a cone
- Place the filter paper point down into a filter funnel that's sitting in the neck of a container
- Pour the mixture into the filter paper
- 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
- Pour the solution into an evaporating dish
- Place the evaporating dish on top of a tripod and gauze and place a Bunsen burner underneath
- Slowly heat the solution. The solvent will evaporate. Eventually the solid will form
- Keep heating the evaporation dish until all you have left is a dry solid
Crystallisation
Takes more time but can produce crystals
- Place an evaporating dish on top of a tripod with a gauze mat. Place a Bunsen burner underneath
- Pour the solution into the evaporating dish and gently heat it
- 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
- Filter the crystals out of the solution, and leave them in a warm place to dry