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Edexcel IGCSE Chemistry 1.11 Chromatograms

Practise reading chromatograms to compare dyes, spot positions, solubility and mixture composition from paper evidence.

Syllabus
First assessment 2019
Course
Chemistry 4CH1

Exam points

  • link spots at the same height or Rf value to the same dye in different samples
  • use the number of spots to decide whether a colouring contains one or several dyes
  • explain why a spot left on the start line shows an insoluble dye or uncertain mixture

1.11 Chromatograms question 1

[Maximum number: 6]

A student uses paper chromatography to investigate the dyes in five different inks, V, W, X, Y and Z.

This is what she uses.
- a beaker
- a piece of chromatography paper with a pencil line drawn near the bottom of the paper
- a solvent
- inks V, W, X, Y and Z

Question (a)

(a)

The chromatogram shows the results for inks V, W, X, Y and Z.

Figure for Question (a) — Edexcel IGCSE Chemistry
[ 6 ]

Question (i)

(i)

Explain which ink contains a dye that is insoluble in the solvent.

[ 2 ]

Question (ii)

(ii)

Explain which two inks contain the dye that is likely to be the most soluble in the solvent.

[ 2 ]

Question (iii)

(iii)

Explain which two inks may contain only one dye.

[ 2 ]
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