Un-Mixing a Mixture? (Topic 3)

Un-mixing a mixture? (Topic 3)

In this activity we will explore the properties of cereal and find out how much of the cereal is really cereal, and how much stuff is really added to the cereal.

Materials:

· Zip-loc bag with cereal

· Water

· Magnet

· Magnifying glass (optional)

Pre lab Questions:

1. Describe the cereal inside the bag, what do you observe? ______

______

2. If you had to classify the cereal inside the bag, would it be a mixture, a solution, a pure substance? Explain ______

______

Procedures:

1. Add water to the bag with cereal and close tightly, trying to release as much of the air inside the bag as possible.

2. Gently massage the bag, mixing the cereal and water until a uniform liquid mixture of cereal and water is formed. Wrap the bag with the cereal – water mixture around the magnet, and let it stand for five minutes.

3. Is this mixture a solution? Explain. ______

______

4. After 5 minutes, gently observe the mixture inside the bag around the magnet. Do you see anything? Gently move the magnet over the bag (still touching the bag) and describe what you see. ______

______

5. How does this observation change your perception of the cereal? Is the cereal a pure substance or is it a mixture?

6. How did adding water to the cereal help to determine that the cereal was a mixture? Explain.

______

Teacher Notes:

Types of Mixtures

Heterogeneous / Homogeneous
Solid–Solid / Concrete (sand and rock) / Known as alloys:
- Stainless steel (iron and carbon)
- Brass (copper and zinc)
Solid–Liquid / Known as suspensions:
- Chalk and water
- Vegetable soup (vegetables and water) / - Salt water (salt and water)
- Kool-Aid® (solid ingredients and water)
Solid–Gas / Smog (carbon and air)
Liquid–Liquid / Known as emulsions:
Density column (various liquids that do not mix) / - Vinegar (acetic acid and water)
- Mayonnaise (stable emulsion of oil, lemon juice, and egg yolk)
Liquid–Gas / Foam / Seltzer water (CO2 and water)
Gas–Gas / Air (nitrogen and oxygen)