week 4 : Chromatography

Chromatography is a chemical technique for separating mixtures of coloured chemicals. Forensic scientists use chromatography to separate the different coloured pigment in writing ink to find out which pen was used which will help solve the case.

Paper Chromatography

You draw a pencil line about 2cm from the bottom of the blotting paper all the way across. Then reprisent the number of pens you are testing as crosses, put a small dot of each pen on to the crosses. Put a small amount of water into a beaker then stand the paper up in it, leave it for a short amount of time. Each of the pens colours will have separated into other colours : as shown in the picture above.