Paper chromatography can be used to separate metal ions in a mixture and identify them by comparison with known samples of metal ions (A–E).

1. (a)Draw a labelled diagram to show the apparatus used in paper chromatography. On your diagram show • the solvent, • where the mixture of metal ions and known samples of metal ions are placed at the start of the experiment.[2]
2. (b)The completed chromatogram is shown below. [Figure showing a chromatogram with a solvent front line, a base line, and five spots labelled A, B, C, D, E, plus a spot labelled 'mixture'. Spot 'mixture' aligns with spots B and E on the base line. Spot A is furthest from the base line, followed by C, D, B, and E.]
3. (b)(i)Which of the metal ions, A–E, were present in the mixture?[1]
4. (b)(ii)Calculate the Rf value of metal ion A. Rf value =[1]
5. (c)Ammonia can be used as a locating agent for some metal ions on the chromatogram.
6. (c)(i)Suggest why a locating agent may need to be used.[1]
7. (c)(ii)Aqueous ammonia is added slowly to aqueous copper(II) sulfate until the ammonia is in excess. Describe what you would observe as the ammonia is added.[2]
8. (c)(iii)Construct the ionic equation, with state symbols, for the reaction of aqueous copper(II) sulfate with aqueous sodium hydroxide.[2]

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