Inorganic identification tests

• Distinguish between aldehydes and ketones using acidified potassium dichromate (VI) solution

  aldehydes change potassium dichromate solution from orange to green

  ketones give no colour change
• Distinguish between aldehydes and ketones using Fehling’s solution

  aldehydes forms a red precipitate when heated with Fehling’s solution

  ketones give no changes
• Distinguish between aldehydes and ketones using Tollens’ reagents

  ketones give no changes

  aldehydes form a silver mirror when heated with Tollens’ reagent
• Observations when carboxylic acids react with sodium carbonate

  solid disappears, fizzing
• Observations when carboxylic acids react with sodium hydroxide solution

  Mixture heats up
• Observations when carboxylic acids react with aqueous ammonia

  Smell disappears
• Observations when carboxylic acids react with alcohols


  Sweet smell (pear drops)
• Observations when carboxylic acids react with phosphorous pentachloride 


  Solid disappears, misty fumes, mixture heats up
• Observations when acyl chlorides react with water

  Misty fumes, mixture heats up
• Observations when acyl chlorides react with alcohols


  Same as water but less vigorous
• What’s observed when methyl-3-nitrobenzoate is prepared?

  Cream solid
• What is observed when aspirin is prepared?


  product appears as white crystals
• Observations when amino acids react with sodium carbonate

  Fizzing, solid disappears
• Observations when amino acids react with copper (II) sulfate solution

  Solution turns dark blue
• Observations when amino acids react with nitrous acid

  Bubbles given off
• What observed when phenol/phenylamine with benzenediazonium chloride?


  Yellow precipitate
• Colours of vanadium oxidation states:

  V<2+>

  V<3+>

  VO<2+>

  VO2<+>

  Violet

  green

  blue

  yellow
• Titration of I2 with S2O32- using starch:

  add the thiosulphate solution until

  the solution is straw/yellow

  coloured and then add starch;

  turns from blue-black to

  colourless at endpoint
• Titration of Fe2+ with MnO4:

  no indicator required as the acidified solution changes from colourless to pink
• Ligand replacement

  reaction - observations when hexaaquacopper(II)

  ions react with ammonia solution

  blue precipitate forms

  addition of excess ammonia solution a dark blue/deep blue solution forms
• Ligand replacement

  reaction - observations when

  hexaaquacopper(II) ions react with conc. HCl

  blue solution changes to yellow
• Qualitative detection test for Cr<3+>

  green-blue precipitate soluble in

  excess sodium hydroxide solution.
• Qualitative detection test for Mn<2+>


  white precipitate slowly turning brown/black on standing;

  insoluble in excess sodium hydroxide solution/ ammonia

  solution
• Qualitative detection test for Fe<2+>

  green precipitate; insoluble in excess sodium hydroxide solution/ ammonia solution
• Qualitative detection test for Fe<3+>

  brown precipitate; insoluble in

  excess sodium hydroxide solution/ammonia solution
• Qualitative detection test for Co<2+>

  blue precipitate

  insoluble in excess sodium hydroxide

  solution

  soluble in excess ammonia solution forming a yellow solution which changes to brown on standing
• Qualitative detection test for Ni<2+>

  green precipitate insoluble in

  excess sodium hydroxide solution;

  soluble in excess ammonia solution to form a blue solution
• Qualitative detection test for Cu<2+>

  blue precipitate

  insoluble in excess sodium hydroxide

  solution

  soluble in excess ammonia solution to form a dark blue solution
• The colour of the aqueous complex Cr<3+>

  green
• The colour of the aqueous complex Cr2O7<2->

  Orange
• The colour of the aqueous complex CrO4<2->

  Yellow
• The colour of the aqueous complex Mn<2+>

  Pink
• The colour of the aqueous complex Fe<2+>

  Green
• The colour of the aqueous complex Fe<3+>

  Orange/yellow
• The colour of the aqueous complex Co<2+>

  Pink
• The colour of the aqueous complex Ni<2+>

  Green
• The colour of the aqueous complex Cu<2+>

  Blue
• The colour of the aqueous complex V<2+>

  Violet
• The colour of the aqueous complex V<3+>

  Green
• The colour of the aqueous complex VO<2+>

  Blue