Filtration and Crystallisation Flashcards
What are filtration and crystallisation used for?
Separating mixtures.
What is filtration used for?
To separate an insoluble solute from a liquid or solution.
What are the reasons to use filtration?
To purify a liquid or solution by removing solid impurities.
To separate a solid you want from a liquid. (e.g. to separate crystals from a solution after crystallisation)
What is needed for filtration?
A funnel, filter paper, and a container/beaker.
What is crystallisation used for?
To produce solid crystals from a solution, or remove impurities from a mixture.
How does crystallisation work?
The solution is heated to remove enough solvent to produce a saturated solution. The saturated solution is allowed to cool, and crystals form in the solution. The crystals are separated from the solution and dried.
What is needed for crystallisation?
An evaporating bowl/container, and a method of heating (e.g. bunsen burner, beaker + hot water).
Why does filtration work?
The filter paper has tiny pores, they are large enough to let water molecules and dissolved substances through. They are small enough to stop insoluble solid particles going through.
Why does crystallisation work?
Solubility is the amount of solute that dissolves in a given amount of solvent, at a given temperature.
Crystallisation works because the solubility of the solute decreases when the solution cools.
Crystals form from the excess solute.
