Topic 2 - States of Matter and Mixtures Flashcards
Pure substance
One single element or compound
Testing purity
Comparing melting points with expected and actual. Also if the MP is a specific point not a range.
Simple distillation
Separating liquid from solution.
Limitation of simple distillation
The 2 components must have very different boiling points. If not fractional distillation is used.
Fractional distillation use
Mixture of liquids
Filtration
Separating an insoluble salt from liquid
Crystallisation
Separating a soluble salt
Chromatography
Separate a mixture of soluble substances
Mobile phase
Where molecules can - water (solvent)
Stationary phase
Where molecules can’t move, paper
Why pencil is used in chromatography
It’s insoluble so won’t move.
If a spot on chromatography doesn’t move
Insoluble
Why chemicals move up chromatography paper.
They dissolve in water and are taken with it up the paper.
Time taken for chromatography (how far)
How soluble
How attracted to stationary phase
Colourless chemicals on chromatogram
Spray with locating agent
Rf Value
Distance travelled by solute(chemical)
Distance travelled by mobile phase (water)
SRM and Chromotography
Standard reference materials, used to compare and identify a substance.
Purity test using chromatography
If there is only 1 spot it’s pure.
Sources of UK water
Surface water - lakes, rivers, reservoirs
Ground water - aquifers (rocks trap water underground)
Waste water - from contaminated water from industry
Filtration from water treatment
Wire mesh screens out twigs, gravel, sand
Sedimentation
Iron or aluminium sulfate are added to water to make fine particles clump together
Chlorination and water treatment
Cl2 is bubbles through to kill bacteria or microbes.
Distillation and water treatment
In dry countries water is distilled. It requires lots of energy for high amounts.
Use of deionised water (distilled)
Ions are removed which could interfere with reactions.
