GEF

Unit 3  |  Water Use and Human Water Systems 86 GROWYOUR KNOWLEDGE Oil does not dissolve in water. It forms a thick layer on the surface. One of the challenges industry has faced in trying to improve water efficiency is how to remove oil fromwater so the water can be reused. With a partner or small team, research the problems caused by water contaminated by oil and the solutions industries are developing so they can improve water efficiency. Then, conduct this simple experiment to learn about one way to separate oil and water. You will need: ■■ Empty, clean 2-liter bottle with cap. ■■ Water ■■ Cooking oil, such as vegetable oil or canola oil ■■ A pin long enough and strong enough to pierce the bottle and the bottle cap ■■ Two empty clean bowls large enough to hold the water and the oil 1. Combine equal parts water and oil in empty, clean 2-liter bottle. You can use cooking oil, such as canola or vegetable. 2. Leave the cap off the bottle and let it sit until the oil floats to the top of the solution. 3. Poke a hole with a pin in the top of the bottle cap. Screw it on, and tighten it. 4. Hold the bottle over a container to catch the water. Poke a small hole with a pin in the bottom of the 2-liter bottle, and allow gravity to pull the water out. 5. Place your finger over the hole when the water is close to being drained to stop the flow. 6. Keeping your finger in place over the hole in the bottom, put your finger over the pinhole on the bottle cap. 7. Move the bottle over the second container, turn the bottle upside down, and remove your finger from the hole in the bottle cap. Allow gravity to pull the oil out of the hole. 8. Place your finger back over the hole when the oil is close to being drained. 9. You will have some oil and some water left over where the two solutions meet. Discard the remaining mixture. 10. Write a lab report to explain the experiment.