Milk, Food Coloring, & Surfactants

Friday, August 23, 2013:

Bob Stoddard and I were assigned to figure out why the food coloring reacted the way it did in this experiment:

Dancing Milk

We were given the option to test anything pertinent in figuring out why the food coloring rapidly dispersed at the touch of the dish soap.

We hypothesized that this reaction happened at the bonding of the parts of the dish soap that lower the surface tension between two liquids and the fat in milk and that the fat there was in the milk, the more intense the reaction was. To test this hypothesis my partner and I repeated this experiment with three different milks: whole milk, 2% Milk, and Skim Milk.

We set up the three petri dishes with the three different milks and a few drops of food coloring in eah. We chose one soap and added a drop of it in each dish. We found that the:

Skim milk had a slow and short reaction.
2% milk had an instant and short reaction.
Whole Milk had an instant and long lasting reaction.

Our hypothesis was proved correct because the whole milk, having the most fat between the three, reacted the most intensely.

At the end of the block, the class came together and discussed what we found. Everybody had different test that all proved in one way or another that the reaction was caused between the dish soap and the lipids in milk. We learned that dish soap, along with detergent and other soaps, are called surfactants and they work as agents that can reduce the surface tension of a liquid and thus allow it to foam or penetrate solids. This proves why the food coloring moved the way it did.

Wonder what we are doing next class?