Purity, formulations and chromatography

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Question 16
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A student investigated purple ink using paper chromatography.

a.

The purple ink contains 72% red dye and 28% blue dye. Determine the simplest whole-number ratio of red dye : blue dye in the purple ink.

[2]
b.

In the chromatogram, the student made the following measurements:

  • the distance moved by the red dye = 4.8 cm
  • the distance moved by the solvent = 8.0 cm

Calculate the RfR_{\text{f}}Rf​ value of the red dye using the equation:

Rf=distance moved by dyedistance moved by solvent R_{\text{f}} = \frac{\text{distance moved by dye}}{\text{distance moved by solvent}} Rf​=distance moved by solventdistance moved by dye​
[2]
c.

Under the same experimental conditions, if the student used a different purple ink formulation containing 60% red dye and 40% blue dye, state what would happen to the RfR_{\text{f}}Rf​ value of the red dye.

[2]

Purity, formulations and chromatography Questions

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