T1 - Filtration, Evaporation, Crystallisation Flashcards
What is a solvent?
A solvent is a liquid in which substances can dissolve.
What does soluble mean?
What does insoluble mean?
Soluble -Solid substances that can dissolve in liquids
Insoluble - Solids that cannot dissolve in liquids.
What separation technique would you use for insoluble solids?
What separation technique would you use for soluble solids?
Filtration.
Evaporation and Crystallisation
How does filtration work?
Filter paper is folded into a cone shape over the beaker. The insoluble solid and liquid mixture is poured through. The liquid passes through the filter paper. The insoluble solid is left in the filter paper.
How does evaporation work?
The solution is poured into an evaporating dish. The solution is slowly heated by a Bunsen burner. The solvent will evaporate and the solution will get more concentrated. Eventually, there will only be dry crystals left.
What are the positives and negatives of using evaporation?
Positive - quick and easy
Negative - Can only be used if the solid doesn’t break down when heated (thermal decomposition).
How does crystallisation work?
- A solution is placed in an evaporating basin and heated with a Bunsen burner.
- Once some of the solvent has been evaporated or when crystals start to form remove the dish from the heat and leave it to cool.
- Crystals are formed.
- The crystals are left in a warm place to dry.
How would you separate a mixture containing insoluble and soluble solids?
For example rock salt.
- Grinding - Make sure that the salt crystals are small so will dissolve easily.
- Dissolving - Put the mixture into water and stir, the salt will dissolve but the sand won’t
- Filtering - Filter the mixture, the grains of sand won’t fit through the tiny holes in the filter paper so they collect on the paper instead. The salt passes through the filter paper as it’s part of the solution.
- Evaporation - Evaporate the water from the salt so that it forms dry crystals.
