Colours of the Rainbow
This is a fun and easy video experiment that uses science to explore the variety of colours that are found in each coloured marker. Children love using coloured markers but rarely think of the multiple colours within each single marker. This is a fun sensory science experiment or video demonstration.
Methodology
Materials
- Coloured Markers
- Jam jar/glass
- Water
- Filter Paper/Coffee Filters
- Teaspoon/Dropper
Precautions
- Coloured markers may stain skin and clothes.
- Wash hands after the experiment.
Method
- Fold Coffee Filter paper in half, four times until you are left with a small wedge shape
- Open out the folded filter paper to reveal a line-creased circle.
- Put a dot from each of the coloured markers on each section, 1-2 inches from the centre, forming a circle of coloured dots.
- Rest filter paper on top of an open jam jar/glass and with a dropper/teaspoon, let a few drops of water fall onto the centre of the paper.
- Watch what happens as the water is absorbed into the paper.
Teacher Notes
This process is called chromatography. (The word “chromatography” is derived from two Greek words: “chroma” meaning colour and “graphein” to write). Chromatography is a way of separating mixtures of different chemicals. For example, pen inks are often made up of a range of different colours. The different molecules in the ink have different solubilities. Solubility is the ability of the ink to dissolve in different fluids, for example water. The fluid that the ink molecules dissolve in is called a solvent (water in this case). Because of the different characteristics of the molecules in the ink, they travel at different speeds when pulled along a piece of paper by the solvent. For example, black ink contains several colours. When the solvent flows through a word written in black, the molecules of each one of the colours behave differently, resulting in a sort of “rainbow” effect. The water helps these colours to separate on the paper. Chemists Chromatography in laboratories to separate out mixtures of chemicals. The chromatography experiment is popular amongst all years while also being educational, students get to experience inquiry, predict the colour make up of each colour and using, observation and teamwork skills explore this separation technique. Following this, a range of extension activities can be conducted in which students obtain and present evidence.
Extension Activities and Worksheets
Every experiment comes with three worksheets, one for early, middle and upper years. They can be easily copied and given to students after the activity or for homework. Access to worksheets is available in the teacher resource pack to Kitchen Chemistry.
