Kaleidoscope Milk Lab

Name: ______Date: ______Block: ______

Kaleidoscope Milk Lab

Background Information:

The role of milk in nature is to nourish and provide immunities for young mammals. Milk’s general composition consists mostly of water with equal parts of fat, protein, and sugars. Milk also contains important vitamins and minerals. Milk is classified into different types based upon the amount of fat. Skim milk contains 0g fat per 250 mL serving; 2% milk contains 2g fat per 250 mL serving; Whole milk contains 8g fat per 250 mL serving; Half & half cream contains 16g fat per a 250mL serving.

If raw milk is left to stand, the fat will separate from the milk, rise, and form a cream layer. To prevent this from happening to the milk you buy at the store, the milk goes through a process called homogenization. Homogenization of milk breaks up the fat into very small fat globules and spreads them throughout the milk. The fat globules (0.1 to 15 µm in diameter) are basically suspended uniformly in the milk.

Milk is a complicated substance made up of many parts that are attracted to some substances while repelling others. These interactions cause milk to act in an interesting way when mixed with substances such as dishwashing soap. Soap cleans dishes by breaking up fat or grease and allowing it to flow in the water down the drain. Food coloring is mostly water with added dye particles. You will discover an interesting property of milk by mixing different types of milk with food coloring and dishwashing soap. You will examine the amount of movement of the milk and food coloring before and after soap is added.

Materials: Liquid Soap Food Coloring Toothpicks Petri dishes

Skim (0%) milk 1% milk 2% milk Whole milk Half & half

Pre-Lab Questions:

1. What are the major components (ingredients) in milk? ______

2 What is/are the major component(s) in food coloring? ______

3. Explain the differences between the four types of milk you will test in lab. ______

4. In your own words, explain the process of homogenization. ______

5. In your own words, explain how dishwashing soap cleans your dirty dishes. ______

6. Complete the chart below:

Hypothesis:

1. Predict what will happen (same movement, more movement, less movement) when you add the food coloring to the different types of milk. Rank the milks from least to most movement. Provide an explanation for your prediction.

Least Movement of Food Coloring ______

______

______

______

Most Movement of Food Coloring ______

Explanation: ______

2. Predict what will happen (same movement, more movement, less movement) when you place the soap in the different types of milk. Rank the milks from least to most movement. Provide an explanation for your prediction.

Least Movement of Food Coloring with Soap ______

______

______

______

Most Movement of Food Coloring with Soap ______

Explanation: ______

Procedure:

1. Place the four Petri Dishes on your lab table. Use scrap paper to label your dishes.

2. Put 10-15 pipettes full of each type of milk into its labeled Petri dish.

3. Place 1 drop of food coloring in each corner of each dish at the same time (four drops per dish total).

4. Wait 1-2 minutes. Record your observations (movement of the food coloring) in the data table.

5. Dip a toothpick in soap and then in the center of one dish. Leave your toothpick there for a minute. Repeat this quickly for ALL other petri dishes so observations can be made at the same time. Observe what happens. Record your observations in the data table.

6. Make a sketch of one of the Petri dishes and use color to show what you saw before and after the soap was added.

7. Take turns dipping the toothpick into many different places in the dish. Observe what happens.

8. Pour the used milk down the drain with lots of water. Clean each Petri dish with lots of soap and water then completely dry with paper towels. Return all materials to the tray and clean your lab area.

Observations:

Sketch:

Discussion/Conclusion:

1. Did you collect qualitative or quantitative data in this lab? Explain your answer.

2. Based on the information in your data table, rank the four milks in order of increasing activity (least movement of food coloring to most movement of food coloring) when the food coloring was added.

Least Movement of Food Coloring ______

______

______

______

Most Movement of Food Coloring ______

3. Was your hypothesis supported or rejected by this data? ______

4. Describe the difference in the water content of the four kinds of milk to explain any differences you noted for the different types of milk.

5. Based on the information in your data table, rank the four milks in order of increasing activity (least movement of food coloring to most movement of food coloring) when the soap was added.

Least Movement of Food Coloring ______

______

______

______

Most Movement of Food Coloring ______

6. Was your hypothesis supported or rejected by this data? ______

7. Describe the difference in the fat content of the four kinds of milk to explain any differences you noted for the different types of milk.

8. How does dishwashing detergent clean your dishes?

9. What did you learn from doing this experiment?

TEACHER EXPLANATION--Milk contains drops of fat, which do not mix with the water-soluble food coloring. The Cohesive force between milk molecules allow the food coloring to hold its dropped shape. Whenever the dish washing liquid touches the milk it breaks up the drops of fat which the spread out, allowing the food coloring and milk to mix.

Milk contains a lot of things, but two of its main components are water and fat. The two are mixed together well in what is called an emulsion (which is where the two liquids are mixed together, but it you could could look closely enough, you would find that there are lots of tiny little bits of each). The fat gives the milk a high surface tension, so the food colouring floats easily on the top and doesn't spread very much.