Explain how dyes are separated by paper chromatography.

For the technique of chromatography, there are two 'phases', the stationary phase and the mobile phase. In paper chromatography, the stationary phase is the paper and the mobile phase is the water. The paper chromatography set up is a beaker with a small amount of water in with the paper placed upright, resting on the side of the beaker. Any dyes that are to be analysed should be spotted on a pencil line drawn about an inch from the bottom of the paper, it is important that this line is drawn with pencil otherwise it'll blur.During the experiment, the mobile phase (water) moves slowly up the stationary phase (paper), dragging the dyes with it. The streaks of different colours seen when the dyes move up the paper is due to different strength of interaction with the mobile phase (water). Some dyes are more soluble in the water and so will move further up the paper, and each dye will have a different interaction with the paper. This means that they are carried different distances up the paper and are visibly separated.