Topic 8 - Chemical analysis Flashcards
what is a pure substance
a pure substance is a single element or compound, not mixed with any other substance
what is formulation
a formulation is a mixture of compounds in measured quantities that has been designed as a useful product.
formulations include fuels, cleaning agents, paints, medicines, alloys, fertilisers and foods
describe paper chromatogprahy
- a start line is drawn near the bottom of the paper. the mixture is spotted on the line.
- a beaker is filled with small amounts of solvent
- paper is hung on a rod and placed in a beaker
- solvents travel up the paper, thus separating the components
- before solvent level reaches the end, the paper is taken out and the finish line is marked. the paper is dried
- the procedure works when different compounds have different affinities for the solvent/paper. stronger attraction for the paper - travels slowly with the solvent
- paper is called the statinonary phase - it doesn’t move, solvent is in the mobile phase
describe the test for hydrogen
pop with a burning splint over gas
describe the test of oxygen
glowing splint relights
describe the test of carbon dioxide
turns limewater milky
describe the test for chlorine
bleaches damp litmus paper and makes it white
describe the flame test result for lithium compounds
crimson red flame
describe the flame test results for sodium compounds
yellow flame
describe potassium compounds flame test results
lilac flame
describe the calcium compounds flame test results
orange red flame
describe the copper compound flame test results
green flame
describe the test for carbonate anions
add dilute acid
fizzing is observed, as CO2 is released
describe sulphate tests
add a solution containing Ba2+ cations
white precipitation of BaSO4
what are instrumental methods
they are accurate, sensitive and rapid methods which are useful when the amount of sample is very small
