Filtration and crystallisation Flashcards
Describe the technique for filtration.
1.Place a piece of filter paper in a funnel and put the funnel over a beaker.
2.Pour your mixture through the funnel.
3.Any insoluble solids will be caught by the filter paper,we call this the residue.
4.Any liquid or dissolved substances will pass straight through, we call this filtrate.
What is filtration?
Filtration is a technique that is used to separate insoluble solid from a liquid.
What is evaporation used for?
Evaporation is used to separate a soluble solid from a liquid.
Describe the technique for evaporation?
Heat your solution until all of the solvent evaporates and only solid remains.You can heat it in several ways like with a evaporation dish on top a Bunsen burner.
Describe the technique for crystallisation.
1.Pour the solution into an evaporating dish.
2.Heat it using a Bunsen burner.
3.Stop heating it when crystals start to form this is the point of crystallisation after that let it cool down
4.Either leave it to allow the rest of the water to evaporate or filter out the crystals using filter paper and a funnel
5.Dry the crystals in a warming oven or desiccator.
What is the benefit of using crystallisation rather than evaporating as a separating technique?
The excess heat used in evaporation can sometimes cause the crystals to break down by thermal decomposition.
How would you isolate the sand and salt from a mixture of salt and sand.
1.Place the mixture in water and stir.The salt will dissolve but the sand won’t.
2.Pour the mixture through filter paper and funnel.The sand will get stuck on the filter paper.
3.Evaporate the water by heating.This will leave behind the salt.
Does sand and salt not dissolve in water.
Salt does dissolve in water but rocks and sand do not dissolve in water.
What is chromatography used for?
Chromatography is used to separate out substances that have been dissolved.
What is a ‘pure’ substance?
A pure substance is one that only contains one type of element or compound.
What is a solution?
A solution is a mixture that contains a solute (a solid) dissolved in a solvent (the liquid.)
