Paper chromatography

MATERIALS Paper towel Red, yellow and blue food colouring 1 glass Spoon Water Scissors An eye-dropper Water INSTRUCTIONS Drop one drop of red, one drop of yellow, and one drop of blue food colouring together on a glass. Mix the three drops together and observe the mixture. Cut a 3 cm strip of paper towel. Using the eye-dropper put a small drop of the food colour mixture in the centre of the paper towel strip about 3 cm from one end. Fill the other glass with water. Place the end of the paper towel strip with the food colouring dot into the water. Make sure the water does not touch the food colouring. Observe for 5-10 minutes. The water separates the food colouring mixture with separate portions of red, blue and yellow on the paper towel strip. WHY? Because the water creeps along the surface of the paper and dissolves the particles of colour. The components of the mixture move along the paper. The different colours do not move at the same speed because they all have different attractions to solvent and paper. WHAT DO YOU THINK ABOUT IT? WRITE YOUR OPINIONS!