Chromatography And Pigments

Chromatography and pigments.

When the solvent reached the ink spot, it dissolved the molecules of coloured chemicals. Molecules of these chemicals differed in sizes, therefore the smallest solute molecules travelled as quickly as the solvent and got carried till the top of the chromatography paper. Larger molecule travelled slower, so they stayed behind, the distance was seen on the paper after the reaction finished. Different polarity of each molecule, gives molecules different solubility in solvent. Over all we can say that some colour molecules travelled faster than others, depending on the size of the molecules, and how soluble molecule is.

Water is a most polar solvent in mobile phase, therefore paper is the most suitable compound in stationary phase. Paper is made of cellulose fibres and the main point about cellulose chemical structure is that it has OH groups.