What constitutes the stationary phase in paper chromatography?

In paper chromatography, the stationary phase refers to the medium or material that does not move throughout the process. In this context, the paper itself acts as the stationary phase. It provides a surface where the various substances in the mixture can interact. As the solvent moves through the paper, it carries the dissolved substances with it. However, since the paper remains fixed in position, it allows for the separation of the components based on their different affinities to the stationary phase versus the moving solvent.

This interaction leads to the different rates of movement for each substance, enabling them to be effectively separated and identified. Understanding that the stationary phase is the unmovable medium is critical for grasping how chromatography functions to separate mixtures based on their chemical properties.