Question

Why should the paper chromatography strip not touch the walls of the test tube during the analysis of a mixture?

Answer 1

The paper chromatography strip should not touch the test tube walls to prevent irregular advancement of the mobile phase and ensure accurate chromatographic separation of mixture components.

Step-by-step explanation:

The reason the paper chromatography strip should not touch the walls of the test tube during the analysis of a mixture is to ensure that the mobile phase moves up the paper evenly via capillary action. If the strip touches the walls, it can cause irregular capillary action and thus uneven advancement of the mobile phase, which may lead to distorted or smeared bands. This can affect both the separation and the accurate interpretation of the chromatographic results. It is essential that each component of the mixture is allowed to migrate at its own rate for optimal separation, which is based on the differential partitioning between the mobile and stationary phases.

Answer 2

Because the solvent will release to the walls of the test tube and your chromatography will be incorrect.

Step-by-step explanation:

When you use a paper strip and a solvent in an experiment, you put your sample in the middle of the paper, in that way, the solvent will rise up, separating the different compounds in your mixture, and at the same they are going to be aligned, so will be easier to identify the number of compounds that you have. If you do not put it straight, you will not see clearly the separation, because some compounds will be overlap.