Disappearing Colors

Today we are exploring the world of bleach. As you may know, water and bleach are very different. If you do laundry or (kids: if you help) then you may know not to put anything that has colored fabric in the whitewash. Have you ever wondered why this happens? Water and Bleach look similar at a glance but they are very different. Bleach is very alkaline but water is a neutral pH. Chemically, that is a big difference. Let’s see how this effect vivid colors!

What You will need:

2 clear cups
food coloring
water
bleach

What to do:

First fill one of the clear cups 3/4 full with room temperature tap water.
Then add 2 drops of food coloring to the water and observe the vividness of the food coloring while it mixes in the water.
Next fill the other cup 1/4-full with bleach before mixing it with the colored water.
Pour the mixture back and forth between cups 3 or 4 times.
Lastly let the mixture sit, in open air, for several minutes, observing the changes in color.

Also Try…

It will also be fun to try this out with different types of bleach, think different brands of bleach, scents or concentrations. You could also change the water by trying this with tap. distilled, or ionized water. Make sure to keep either the bleach the same throughout the experiments or the water you need to have one variable or consistent to observe the differences.

Explanation

Bleach fades colors, this process is called bleaching or whitening and is a result of either oxidizing or reducing. Oxidizing bleaches work by breaking chemical bonds between the molecules of dye. The resulting molecules (after being oxidized) will no longer absorb visible light, resulting in faded color. Bleach can also fade colors through reducing. Reducing bleach changes double bonds into single bonds. The reducing process results in a molecule that is unable to absorb visible light.

Water is able to “fade” color through dissolution. The amount of color is dissolute throughout a larger volume when added to water. The molecules do not actually fade. Rather, the molecules are just spread out, giving the impression that they have lost color.