Testing for metal ions

Mind Map by dpatel383, updated more than 1 year ago
Created by dpatel383 about 7 years ago


A Levels Chemistry C3 Mind Map on Testing for metal ions, created by dpatel383 on 05/18/2013.

Resource summary

Testing for metal ions
1 flame tests (3 common ways)
1.1 different metal ions give off different coloured flames when solutions of those ions are heated in a bunsen burner flame
1.2 spray metal compound solution into a bunsen burner flame
1.3 use wooden splints soaked overnight in the metal compound solution
1.4 use a loop of nichrome wire to hold a small volume of solution in the flame
1.4.1 if nichrome wire used - must be cleaned between each flame test.... dip loop into concentrated hydrochloric acid and hold in flame.....process repeated until wire no longer affects the flame colour...... traces of sodium ions are particuarly difficult to remove
2 lithium ( crimson)
3 sodium (yellow)
4 potassium (lilac)
5 calcium (red)
6 barium (green)
7 hydroxide precipitates
7.1 copper and iron form coloured compounds
7.2 coloured hydroxide precipitate is formed when a few drops of sodium hydroxide solution are added to solutions of metal ions
7.2.1 eg Cu+2 + OH = Cu(OH)2
7.3 copper(ii) ( blue )
7.4 iron(ii) ( green )
7.5 iron(iii) (brown)
7.6 aluminium , calcium and magnesium ions form hydroxide precipitate with sodium hydroxide solution.
7.6.1 difficult to tell apart as they are all white though..... aluminium hydroxide precipitate dissolves to form a colourless solution when excess sodium hydroxide solution is added
8 Testing for negative ions
8.1 Carbonate ions
8.1.1 compounds containg carbonate ions react with dilute acids to form carbon dioxide eg.....drops of hydrochloric acid added to calcium carbonate causes bubbling on the surface of the solid
8.1.2 most carbonates are insoluble in water ........HOWEVER sodium carbonate is soluble sodium carbonate solution addded to dilute acid causes brief bubbling
8.1.3 limewater, calcium hydroxide solution is used as a comfirmatory test for production of CO2...........white precipitate of calcium carbonate formed when CO2 is bubbled through limewater Ca(OH)2 (aq) + CO2 (g) = CaCO3 (s) + H2O (l)
8.2 Sulfate ions
8.2.1 barium sulfate insoluble in water BUT not barium chloride white precipitate of barium sulfate forms when barium chloride solution is added to solutions containing sulfate ions eg........... Na2SO4 (aq) +BaCl2 (aq) = 2NaCl (aq) + BaSO4 (s)
8.3 Halide ions
8.3.1 formed by halogens
8.3.2 silver fluoride is soluble in water but other silver halides are insoluble their insolubility is basis for test for the presence of chloride ions bromide ions or iodine ions Precipitate forms when silver nitrate solution is added to solutions containing these ions eg.......NaCl2(aq) + AgNO3 (aq) = NaNo3(aq) + AgCl (s)
8.3.3 halide ion Chloride Bromide Iodide
8.3.4 precipitate formed silver chloride silver bromide silver iodide
8.3.5 colour of precipitate white cream yellow
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