Dancing Milk Experiment

Dancing Milk Experiment
August 22nd 2013

In my first class of Honors Biology, I got to perform the Dancing Milk Experiment. Our class observed this experiment the previous night in a video assigned for homework. In the video, a Q-tip, with the end covered in dish soap, was inserted into the middle of a bowl of milk, which contained several drops of food-coloring throughout. Previously sitting motionless on top of the milk, the drops of food-coloring immediately began to disperse away from the center where the soap was added. By the end of this process, the food-coloring appeared to be spread throughout all of the bowl.

For this experiment, I was paired with Andy Liu. I hypothesized that the reason the food-coloring spread so much was that the chemical bonds in the milk were weakened by the dish soap. Andy believed that the reaction could be predicted through observing the pH of the two substances involved.

The materials that we used included a graduated cylinder, dish soap, water, vinegar, two small plastic bowls, and the different liquids( milk, coffee, orange juice).

In our first experiment, we repeated the example shown in the video, using 2% milk and dish soap. The reaction that we received proved to be consistent with the video. Then we produced a controlled version, using water instead of dish soap. These two experiments can be seen in the video and two pictures below.

Result of 2% Milk & Dish Soap

                                                              Result of 2% Milk & Water

                    This proves that the dish soap is what causes the reaction, for the water had no effect.
                   

We also attempted an experiment where we put vinegar into the 2% Milk rather than dish soap, and it resulted the same as the water, with no reaction.



Then Andy and I switched out the 2% Milk with Orange Juice and conducted a new experiment. The reaction can be seen in the video and photo below.

Result of Orange Juice & Dish Soap

                                      Though a slight reaction occurred, the Orange Juice was
                                          not as reactive with the dish soap as the 2% Milk.


For our next attempt for a reaction, we decided to see if Coffee would react with dish soap. A repeated experiment using Coffee rather than 2% Milk or Orange Juice can be seen in the video below.

                                            The coffee produced only the slightest reaction.


For our last experiment, we decided to try a different milk. We went with the Whole Milk, and the video and pictures below show how that turned out.

Whole Milk & Dish Soap

                                                          Whole Milk & Dish Soap

The reaction was very similar to the 2% Milk, but it appeared that in the Whole Milk the food-coloring went under and popped back up more. I would also say that the reaction containing the 2% Milk occurred faster than the reaction with the Whole Milk.

It is inferred that the combination of dish soap and milk create the greatest reaction. I would say that the order of reactivity with dish soap from greatest to lowest would be milk, then orange juice, then coffee. This seems to disprove the pH theory, since the greatest reaction is milk with a pH of 6.7, then orange juice with a pH of 2.8, then coffee with a pH of 5.0. They are not in a consistent order, so the reactivity does not appear to be related with the acidity of the liquids.