Question

1. This worksheet will help you organize your thoughts for the discussion. Write down some notes based on the questions and prompts below.

a) Paper chromatography uses both a stationary phase and a mobile phase. Describe these two phases. (5 points)

b) Why do different components in the mobile phase move at different rates on the paper? (5 points)

c) One quantitative way to determine the nature of a component of the solute is to determine the retention factor (R_f) of the component. The retention factor is the ratio of the distance traveled by the component to the distance traveled by the solvent. Infer what it means when R_f = 0 and when R_f = 1. (5 points)

Answer 1

Answer:

a) Stationary phase: A solid or liquid which is supported on a solid.In paper chromatography, stationary phase is water.Paper is used to support stationary phase.

Mobile phase: A liquid or gas which flows through the stationary phase and carries the components of the mixture with it. In paper chromatography,mobile phase is the mixture of polar organic solvent with water.

b)Components of the sample will get separate according to how strongly they adsorb with the mobile phase and how easily it dissolves in the mobile phase.

When mobile phase or solvent diffuses up the paper,it dissolves the various components of the sample based on their polarity and solvent polarity.Based on the solubility of the components in the mobile phase, they will move in the paper.Based on different solubility,components of the mixture will move different height in the paper.The more soluble component will migrate greater height in the paper.Less soluble component will move less distance in the paper as it is less soluble in the very polar solvent or mobile phase.

c).If Rf value of the solution is zero, the solute remains in the stationary phase which means solute is immobile.

If Rf value of the solution is equal to1, solute is having no affinity with the stationary phase and it travels with the solvent front.