A Colorful Springtime Chromatography Experiment With Household Items
Have you ever looked at sunlight through a prism or drops of water? If so, you know that the prism can separate the sunlight into many different colors of light — a rainbow. Like sunlight, chemical mixtures can also be broken into their component parts. One way of doing this is a simple technique called paper chromatography. What do you think you will see if you use paper chromatography to look at the components of black ink? Is black ink just black?
- Capillary action
- Mobile phase
Filter paper or coffee filter
Vis-à-vis Pens, Markers, highlighters – any water-based color
Small containers of water
- Start with a piece of filter paper
- Have the child make designs on the paper, using one color at a time
- Use the pipette to place one drop of water on the ink design.
- Watch it diffuse and change colors.
Marker inks are made from many different colored dyes. (This is most obvious with dark colors such as black and purple.) Each dye is made up of different chemicals, some heavier and some lighter, that travel at different speeds as the water moves them up the paper. The heavier dyes will separate out first and move more slowly while the lighter dyes keep moving faster up the paper, creating the tie-dyed or washed out effect. Try to count how many different colors you see on your final product! Try this same activity using Sharpies or other permanent pens and isopropyl alcohol instead of water. Try using water first. What’s happening? The water-based markers are water-soluble and can diffuse in water. The permanent markers are not water-soluble but are alcohol soluble.
Can we make “ink” from items in your garden? Do you think the green in the leaves is just green?