HOLLAND - Our science experiment today deals with food coloring, milk, a Q-tip, and dishwashing soap. These are the ingredients needed to show molecule movement and magnetism. Two percent or whole milk works best, since we need the fat in the milk to help move the molecules and "swirl" some colors.
At one time or another, we all played with magnets. We know "opposite" poles attract, while "like" poles repel. This system reminds me of that, but what's really happening is the movement of molecules. It's also similar to oil and water. The two don't mix, they repel each other.
Get a bowl and fill the bottom with milk. It's got fat in it, plus it's easier to see the results. Put a few drops of food coloring in the middle of the bowl/milk. Use different colors. Take a Q-tip and dip it into dishwashing soap. Next, touch the blob of food coloring in the bowl. Make sure not to stir it. What happens? A burst of beautiful colors!
Milk is mostly water, but it also contains fat. Fats and proteins are sensitive to changes in the milk. The secret of the bursting colors is the chemistry in the drop of soap. Dish soap, because of its bipolar characteristics, weakens the chemical bonds that hold the proteins and fats in the solution. The soap's polar, or hydrophilic (water-loving), end dissolves in water, and its hydrophobic (water-fearing) end attaches to the fat in the milk.
The molecules of fat bend, roll, twist, and contort in all directions as the soap molecules race around to join up with the fat molecules. During all of the fat molecule gymnastics, the food coloring molecules are bumped and shoved everywhere, providing an easy way to observe all the invisible activity. As the soap becomes evenly mixed with the milk, the action slows down and eventually stops.
A great, fun, easy experiment to do at home or in the classroom. Try this one!