“Chromatography at home” experiment
How to separate mixtures with the help of paper and alcohol
Everyone knows about dog races, and even cockroach races. But have you ever seen dyes competing for speed? Get some popcorn and invite your friends around – it’s time to place your bets!
Work in a well-ventilated room and in protective glasses. Observe safety rules when working with concentrated ethanol.
Warning! Only under adults supervision.
Reagents and equipment:
- black and blue markers;
- 96% ethanol;
- sheet of thick paper;
Take a small sheet of thick paper which can fit in a beaker. Make three dots on the paper with markers: black, blue, and a mixture of colors (black + blue). To make the dots on the same level, draw a starting line with a pencil first. Now lower the paper in the beaker with ethanol, about half a centimeter from the bottom. Then seal the beaker, so the ethanol doesn’t evaporate. After half an hour, observe the movement and separation of colors on the paper.
Chromatography is a method for analyzing substances by their separation into components. The method was discovered by Mikhail Tsvet, who separated color pigments of plants. In our experiment, we must select the solvent which is contained the markers. This is usually ethanol.
Due to the capillary effect, the ethanol soaks the paper evenly, taking the dyes with it. The dyes in the mixture react differently with the alcohol, so they rise at different speeds.
Separation is based on this difference in speed.