Mystery Milk Project

Purpose: How does it work? Hypothesize how and why you think that this occurs. What makes the swirling of the food coloring occur? Talk about it with your partners. Then write your ideas in your science journals.

Materials: - Milk -Petri Dish - Food coloring (red, yellow, green, blue) - Dish-washing soap - Cotton swabs

Procedures: 1. Pour enough milk in the pie tin to completely cover the bottom and allow it to settle. 2. Add one drop of each of the four colors of food coloring - red, yellow, blue, and green - to the milk. Keep the drops close together in the center of the plate of milk in a 3, 6, 9, 12 o’clock formation. 3. Find a clean cotton swab for the next part of the experiment. Predict what will happen when you touch the tip of the cotton swab to the center of the milk. It's important not to stir the mix just touch it with the tip of the cotton swab. 4. Place a drop of liquid dish soap (the Dawn brand works well) on the tip of the cotton swab. Place the soapy end of the cotton swab back in the middle of the milk and hold it there for 10 to 15 seconds.

Observed: Look at that burst of color! It's like the 4th of July in a bowl of milk: mini-explosions of color. Step 5. Add another drop of soap to the tip to the cotton swab and try it again. Experiment with placing the cotton swab at different places in the milk. Notice that the colors in the milk continue to move even when the cotton swab is removed. What makes the food coloring in the milk move?

What make the swirling of the food coloring occur? Liquid soap wrecks the surface tension by breaking the cohesive bonds between water molecules and allowing the colors to zing throughout the milk. In this experiment the liquid soap weakens the milk’s bonds by attaching to its fat globules because of its bipolar characteristics (hydrophilic on one end and hydrophobic on the other). The soap's hydrophilic end dissolves in water and its water-fearing end attaches to a fat globule in the milk.

What is it about milk that makes it have surface tension? Since milk is mostly water, it has surface tension like water. The drops of food coloring floating on the surface tend to stay put. Water has surface tension because of the attraction of all of the molecules. In the bulk of the liquid each molecule is pulled equally in all directions by neighboring liquid molecules.

Atom: the smallest basic unit of matter. Compound: atoms of different elements bonded together in a certain ratio. Molecules: two or more atoms held together by a chemical bond. Element: one type of atom (each have different number of protons)

Unique Properties of water This experiment can explain surface tension and polarity. The explanation of surface tension can show all of the things that make water so useful for life. For example, waters surface tension comes from its polarity such that it is attracted to itself. This makes certain things like the capillary effect possible so that plants may “drink” water from the ground. This also explains the structure of ice and why the solid form of H2O is less dense than the liquid stage.

Phospholipid Bilayer This characteristic behavior of water and oil is of critical importance for living things, determining many properties of the cell Phospholipids, the building blocks of the cell membranes, are both hydrophilic and hydrophobic. The hydrophobic pair of fatty acids are embedded in the middle of the membrane. The hydrophilic phosphate projects outward forming hydrogen bonds with a tight, organized layer of water on each face of the membrane.

What is it about soap that allows for oils to be dissolved? Soap has a part of the molecule that is polar and nonpolar. When washing with water alone, it will not dissolve oils, but when soap is added to the water, the polar end of the soap molecules is attracted to the polar end of the water molecules and the nonpolar end is absorbed into the oil. A particle (larger than a molecule) is formed and the oil can be washed away with water.

Homogenization This experiment explains what homogenization of milk is. Milk is made up mostly of water and then equal parts of protein, fats, and sugar. The fat has been broken up and spread throughout the milk (by the process called HOMOGENIZATION) into tiny pieces of fat called globules. When the milk was first placed into the carton, it was still and did not move. Even when the food coloring was added to the milk, things were still quiet. This is because the fat globules were steady and undisturbed. When the soap hits the milk, things begin to move. The soap breaks up the fat globules and lets them spread across the surface of the milk. When you add soap, the weak chemical bonds that hold the proteins in solution are altered. As the globules break and expand, they create movement in the milk. Normally you would never notice this, but the food coloring shows how the surface of the milk moves and changes in response to the soap breaking up the fat in the milk.

How soap works This experiment explains how soap works. Soap has a part of the molecule that is polar and nonpolar. When washing with water alone, it will not dissolve oils, but when soap is added to the water, the polar end of the soap molecules is attracted to the polar end of the water molecules and the nonpolar end is absorbed into the oil. A particle (larger than a molecule) is formed and the oil can be washed away with water. In this experiment the liquid soap weakens the milk’s bonds by attaching to its fat globules because of its bipolar characteristics (hydrophilic on one end and hydrophobic on the other). The soap's hydrophilic end dissolves in water and its water-fearing end attaches to a fat globule in the milk. Soap