Paper chromatography

Paper chromatography is a specific type of chromatography used to separate and analyse components within a mixture. Here's a concise explanation suitable for secondary school students:

Stationary Phase and Mobile Phase:

• In paper chromatography, the stationary phase is a sheet of special paper known as chromatography paper.
• The mobile phase can be either an aqueous (water-based) liquid or a non-aqueous (carbon-based) organic solvent.
• An example of an organic solvent often used is propanone, which is the main chemical in nail varnish remover.

Procedure:

• A small sample of the mixture to be analysed is spotted onto a straight line called the baseline, usually drawn in pencil above the level of the solvent, on the chromatography paper.
• The chromatography paper is then carefully placed in a container with the solvent.

Separation Process:

• As the solvent moves up the paper through a process called capillary action, different components of the mixture are separated.
• The rate at which components move up the paper depends on the choice of solvent.

Dynamic Equilibrium:

• For each chemical in the sample, there is a dynamic equilibrium between the stationary phase (paper) and the mobile phase (solvent).
• The separation of components occurs because they interact differently with the mobile and stationary phases.

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Paper chromatography

Outcome - Chromatogram:

• The result of a paper chromatography experiment is known as a chromatogram.
• A chromatogram is a visual representation that displays how the various components of the mixture have migrated and separated on the paper.
• It allows for the comparison of different samples to a reference material, aiding in the identification of substances.

Overall Separation:

• The effectiveness of the separation depends on how strongly each chemical is attracted to both the mobile and stationary phases.
• This attraction determines the distance each component travels on the chromatography paper.
• Paper chromatography is a valuable analytical technique used in chemistry and other fields to separate, identify, and analyse complex mixtures based on the interactions between different components and the chromatography paper and solvent.