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12021746
C8 - Chemical Analysis
Description
An overview of the C8 topic, Chemical Analysis, from the AQA Chemistry GCSE course.
No tags specified
chemistry
chemical analysis
aqa
gcse
revision
biology
year 11
Mind Map by
Jamie Howell
, updated more than 1 year ago
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Created by
Jamie Howell
over 6 years ago
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Resource summary
C8 - Chemical Analysis
Purity
Only one compound or element - not mixed with anything else
A melting or boiling point can tell you the purity
Specific to element/compounds
Closer = more pure
Impure = lower melting/higher boiling
Formulations
Useful mixture with precise purpose
components measured specifically to perform function
Pharmacy
Consumption
Shelf Life
Concentration
Packaging - ratio/percent of each component = suitable decisions
Paper Chromatography
Mobile phase = molecules can move (liquid or gas)
more time spent here = quicker movement through stationary
Stationary phase = molecules cannot move (solid or thick liquid)
Distance dependent on how soluble they are + how attracted to the paper they are
higher solubility + low attraction = more time in mobile = further
ink = soluble
pencil = insoluble
Rf values
Is a certain substance in a mixture
Measure pure substance Rf (reference) - compare to Rf spots in mixture
Change of solvent = Rf changes
Mixture + Reference spot in all solvents is the same = substance present
Gas Tests
Chlorine = bleaches litmus paper (may turn red before Cl is acidic
Oxygen = relights glowing splint
Carbon Dioxide = bubble through limewater turning it cloudy
Hydrogen = squeaky pop from lit splint
Tests for Anions
Dilute acid for carbonates
1. Add drops of dilute acid
2. Connect test tube to test tube of limewater
3. Carbonate = present if limewater turns cloudy (CO2)
Sulfates
1. Add HCl
gets rid of carbonates which also produce a white precipitate
2. Add barium chloride
3. Sulfate ions = white precipitate forms
Halides
1. Add dilute nitric acid
2. Add silver nitrate
Chloride = white precip
Bromide = cream precip
Iodide = yellow precip
Tests for Cations
Flame Test
1. Clean loop by dipping in HCl + putting through flame
2. Dip in solid/solution
3. Put through flame
Lithium
Sodium
Potassium
Calcium
Copper
Works for single metal ions
Flame Emission Spectroscopy
Heat causes electrons to change energy levels. Drop back = transfer light
Identify wavelengths create line spectrum
Higher concentration = more intense
No two ions have the same line spectrum - can identify more than one ion
Advantages
More accurate
Flame tests rely on the human eye
Very fast/automated
Very sensitive
Sodium hydroxide forms a precipitate
Calcium
Copper (II)
Iron (II)
Iron (III)
Aluminium
White then redissolves to be colourless
Magnesium
Most metal hydroxides = insoluble
Media attachments
Chemical Analysis Rf (binary/octet-stream)
2d28d7a2bba381f12ce8d84f51f042ae (binary/octet-stream)
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