C8 - Chemical Analysis

Jamie Howell
Mind Map by , created almost 2 years ago

An overview of the C8 topic, Chemical Analysis, from the AQA Chemistry GCSE course.

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Jamie Howell
Created by Jamie Howell almost 2 years ago
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C8 - Chemical Analysis
1 Purity
1.1 Only one compound or element - not mixed with anything else
1.2 A melting or boiling point can tell you the purity
1.2.1 Specific to element/compounds
1.2.1.1 Closer = more pure
1.2.2 Impure = lower melting/higher boiling
2 Formulations
2.1 Useful mixture with precise purpose
2.2 components measured specifically to perform function
2.3 Pharmacy
2.3.1 Consumption
2.3.2 Shelf Life
2.3.3 Concentration
2.4 Packaging - ratio/percent of each component = suitable decisions
3 Paper Chromatography
3.1 Mobile phase = molecules can move (liquid or gas)
3.1.1 more time spent here = quicker movement through stationary
3.2 Stationary phase = molecules cannot move (solid or thick liquid)
3.3 Distance dependent on how soluble they are + how attracted to the paper they are
3.3.1 higher solubility + low attraction = more time in mobile = further
3.4 ink = soluble
3.5 pencil = insoluble
3.6 Rf values
3.6.1 Is a certain substance in a mixture
3.6.1.1 Measure pure substance Rf (reference) - compare to Rf spots in mixture
3.6.2 Change of solvent = Rf changes
3.6.2.1 Mixture + Reference spot in all solvents is the same = substance present
3.6.2.1.1
4 Gas Tests
4.1 Chlorine = bleaches litmus paper (may turn red before Cl is acidic
4.2 Oxygen = relights glowing splint
4.3 Carbon Dioxide = bubble through limewater turning it cloudy
4.4 Hydrogen = squeaky pop from lit splint
5 Tests for Anions
5.1 Dilute acid for carbonates
5.1.1 1. Add drops of dilute acid
5.1.2 2. Connect test tube to test tube of limewater
5.1.3 3. Carbonate = present if limewater turns cloudy (CO2)
5.2 Sulfates
5.2.1 1. Add HCl
5.2.1.1 gets rid of carbonates which also produce a white precipitate
5.2.2 2. Add barium chloride
5.2.3 3. Sulfate ions = white precipitate forms
5.3 Halides
5.3.1 1. Add dilute nitric acid
5.3.2 2. Add silver nitrate
5.3.3 Chloride = white precip
5.3.4 Bromide = cream precip
5.3.5 Iodide = yellow precip
6 Tests for Cations
6.1 Flame Test
6.1.1 1. Clean loop by dipping in HCl + putting through flame
6.1.2 2. Dip in solid/solution
6.1.3 3. Put through flame
6.1.4 Lithium
6.1.5 Sodium
6.1.6 Potassium
6.1.7 Calcium
6.1.8 Copper
6.1.9 Works for single metal ions
6.1.9.1 Flame Emission Spectroscopy
6.1.9.1.1 Heat causes electrons to change energy levels. Drop back = transfer light
6.1.9.1.2 Identify wavelengths create line spectrum
6.1.9.1.2.1 Higher concentration = more intense
6.1.9.1.3 No two ions have the same line spectrum - can identify more than one ion
6.1.9.1.4 Advantages
6.1.9.1.4.1 More accurate
6.1.9.1.4.1.1 Flame tests rely on the human eye
6.1.9.1.4.2 Very fast/automated
6.1.9.1.4.3 Very sensitive
6.1.9.1.5
6.2 Sodium hydroxide forms a precipitate
6.2.1 Calcium
6.2.2 Copper (II)
6.2.3 Iron (II)
6.2.4 Iron (III)
6.2.5 Aluminium
6.2.5.1 White then redissolves to be colourless
6.2.6 Magnesium
6.2.7 Most metal hydroxides = insoluble