T8 chemical analysis

single element or compound, not mixed with any other substance

• mixture of compounds in measured quantities that has been designed as a useful product • formulations include fuels, cleaning agents, alloys, medicines, fertilisers e. g. alloys are mixtures of metals, harder than pure metals so have a particular purpose

• start line is drawn near the bottom of the paper. Mixture is spotted on the line • beaker is filled with small amount of solvent • paper is hung on a rod and placed in a beaker • solvent travels up the paper, separating the components • before solvent level reaches the end, paper is taken out and the finish line is marked, paper is dried • 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 stationary phase - doesn’t move, solvent is the mobile phase

distance moved by the spot / distance moved by solvent

H - pop with burning split over gas O - glowing split relights D - turns limewater (Ca(OH)2) milky C - bleaches damp litmus paper and makes it white

lithium compounds - crimson red flame sodium compounds - yellow flame potassium compounds - lilac flame calcium compounds - orange red flame copper compounds - green flame

add dilute acid e.g. HCl fizzing observed as CO2 released

add a solution containing Ba2+ cations white precipitate pf BaSO4 forms

add a solution of AgNO3 (acidified with HNO3) chlorines - white precipitate, silver chloride bromides - cream precipitate, silver bromide iodides - yellow precipitate, silver iodide

accurate, sensitive and rapid methods which are useful when the amount of sample is very small

a) instrumental method used for identifying metal ions in solution or measuring their concentration b) Spectroscope measures the exact wavelength of the light emitted by a metal ion c) That allows for definite identification - sometimes colours are difficult to distinguish. d) Concentrations are found by measuring the intensity of light emitted. The more intense light, the greater the concentration of the metal ion in a solution. e) From the intensity vs concentration graph, you can read off a relevant concentration value at a given intensity.

c - positive ions a - negative ions

copper (II) forms a blue precipitate iron (II) forms a dirty green precipitate iron (III) forms a brown precipitate Al3+, Ca2+, Mg2+ forms white precipitate but only Al(OH)3 dissolves in excess NaOH to form a colourless solution

has a higher affinity for the solvent than for the paper