Separating Mixtures (1) Flashcards
What is filtration used to separate
To seperated an insoluble solid from a liquid
Filtration can also be used in _______________. E.g. Solid impurities in the reaction mixture can be separated out using filtration
Purification
What is crystallisation used to separate
A soluble solid from a solution
How do you crystallise a product
1) Pour the solution into an evaporating dish
2) Slowly heat the solution. Some of the solvent will evaporate hence the solution will get more concentrated. 3) Stop heating when crystals start to form. Remove the dish from the heat and put it in a warm place for the rest of the solvent to slowly evaporate - this forms big crystals
4) Dry the product. Done
What is rock salt
A mixture of salt and sand
Both salt and sand are _____________ but ________ dissolves in water and _________ doesn’t
Compounds
Salt does
Sand doesn’t
How do you separate rock salt
Grinding (with pestle and mortar) Dissolving (in beaker and stir) Filtering (through filter paper and funnel) Crystallisation (evaporate in an evaporating dish) Salt stays on filter paper Salt forms as crystals
Once rock salt has been separated, ________ stays on filter paper and ________ forms as crystals
Salt
Sand
Chromatography works because different dyes will move up the paper at different __________
Rates
The distance the dyes travel up the paper depends on the __________ (e.g water) and the paper you use
Solvent
What is simple distillation used to separate
A liquid from a solution
How does simple distillation work
Solution is heated. The part of the solution with the lowest boiling point rises. That vapour is then cooled, condensed and collected. The rest of the solution is left behind in the flask
What is the problem with simple distillation
It can only separate things with very different boiling points
Example of 2 substances$ separated by simple distillation
Pure water and sea water - water evaporates and salt is left behind
What method of distillation is used if a mixture of liquids have similar boiling points
Fractional distillation
When is fractional distillation used
If a mixture of liquids have similar boiling points
How does fractional distillation work
Put mixture in a flask and put a fractionating column at the top. Then heat it.
Different liquids have different boiling points - so they will evaporate at different temperatures.
The liquid with the lowest boiling point will evaporate first.
Liquids with higher boiling points might also start to evaporate. But the column is cooler towards the top so they will only run part of the way up before condensing and running back down the flask.
When the first liquid has been collected, you raise the temperature until the next one reaches the top
What 2 types of separation can be used to separate rock salt
Filtration
Crystallisation
Components of mixtures are not ____________ joined. Which means that they can be easily ______________
Chemically
Seperated
When can filtration be used (2)
1) If your product is an insoluble solid that needs to be separated from a liquid reaction mixture
2) Purification
What is purification
When solid impurities in the reaction mixture can be separated out using filtration
