Patrick Henry High School | GOT MILK?

Four students sitting at a table.Students in Mrs. Woosley’s chemistry classes observed the reaction of dish soap in milk.  This simple lab illustrates the effects of an emulsifier on the non-polar fat molecules and the polar water molecules in milk.  Food coloring was added to the milk so students could see the emulsified fat molecules move over the surface of the water.

The students observed this mechanism using milk with three different fat contents: whole milk, 2% milk, and skim milk.  They also tested emulsifying potential in three different types of dish soap:  Dawn, Ajax, and Palmolive Antibacterial.  The aggregate complex of soap and fat moves through the milk scavenging for more fat molecules, which causes the food color to swirl with the milk.  Lab groups also had to modify the experiment to test heated milk.  Students had to make careful observations and analyze the results to generate inferences about what is happening in the milk.  Results indicated that the antibacterial soap did not have the same emulsifying potential as the other soaps.  The antibacterial soap did not yield the same vigorous movement of the fat through the milk.  Also, the students observed less vigorous reactions with skim milk (reduced fat content) and more vigorous reactions with heated milk (increased molecular motion).

Contact Person: 
Cindy Woosley