separating techniques Flashcards
what are the five main separating techniques?
filtration, simple distraction, fractional distillation, paper chromatography and crystallisation
what does filtration work on?
filtration is the technique of separating an insoluble solid from a liquid that would be to small to separate using something like colanders so instead you use filter paper
what is the process of filtration?
you pour you mixture of solid and liquid through filter paper which is folded like a cone and fit into a beaker. the liquid passes through the filter paper leaving the solid in the filter paper and the filtered liquid in the beaker.
what is simple distillation?
simple distraction is used to separate a solvent from a solution (producing water from salt solution eg) by using the fact the dissolved solute has a much higher boiling point then the solvent.when the solution is heated the solvent vapour evaporates from the solution. the gas then moves aways and is cooled and condensed
how would you save the liquid with the lowest boiling point when boiling it away in simple distillation?
you would pass it through a cold tube to return it back to a liquid
what is fractional distillation
fraction distillation is used to separate a mixture of liquids. you use the fact they have different boiling points. so when the mixture is heated the vapour rises through a column which is hot at the bottom and cold at the top. when the vapour reaches the cold part of the column (which is below there boiling point) they condense and flow out of the column leaving a pure liquid.
what is paper chromatography?
paper chromatography is a method which recognises that all liquids have diffremts
why is the filter paper successful in separating insoluble solids from liquids?
because it has millions of tiny hoes in it which are large enough to allow molecules and dissolved ions to pass through but not the larger particles of undissolved solids
give an example of the process of simple distillation-
1)salty water is placed in a beaker with a cold tube attached with a different beaker at the other end
2)the salty water is then heated and the pure water vapour begins to rise from the solution passing through the condenser and dripping into the separate beaker
3)all the water is now condensed into a separate beaker leaving pure water in one beaker and salt residue in the other
what are the ways of obtaining the different liquids from the column?
different liquids can be obtained from different parts of the column or by continuing to raise the heat in the mixtures to increase the temperatures in the column
what would the process be for separating ethanol from water?
first you would heat the solution
then the ethanol solution would boil first rise and then condense into a liquid
the water left would then cool and condense
