Practise IB Chemistry HL 2.2.10 by interpreting RF data and explaining separation from competing intermolecular attractions, without relying on unassessed operational detail.
A student wanted to determine what colour inks were mixed to produce black ink and their relative polarities using paper chromatography. The student decided to use two different solvent systems for the separation, both a mixture of propan-2-ol and water. System 1 was 20 % propan-2-ol and system 2 was 80 % propan-2-ol.
Chromatography chambers are sealed while the solvent is moving up the paper.
Explain why it is important to seal the chamber for proper experimental design.
Explain why it is important to keep the start line horizontal and above the solvent level when running the chromatograph
Horizontal start line:
Above the solvent level:
Calculate the retardation factor, , of the red ink in both chromatograms.
Deduce, with a reason, which coloured ink is more polar, red or blue.
The student hypothesized there were more than four coloured inks in the mixture.
Suggest how the student could modify this chromatography experiment to evaluate the hypothesis.
Explain how the separation of inks is achieved using paper chromatography.