Wonderful Weird Water

20 QUESTIONS: WONDERFULLY WEIRD WATER

BACKGROUND: Water is a necessary for the survival of every living organism. While we get no vitamins, minerals, or energy from pure water, it is vital for living things because all chemical reactions that occur in living things, including OUR bodies, occur in water. We are about 70% water, which means for every 100 pounds of body weight, 70 of those pounds are water. Water has some weird properties that make it such a versatile and unique compound. This exercise will demonstrate some of these special properties of water.

MATERIALS: Penny Small paper clip Dish soap Petri dish Forceps Celery 2 Small beakers 10ml Graduate Salt Stirring Rod Colored water Dropper Cooking oil

PROCEDURE:

PART 1: Your Money’s All Wet: Place a penny in a Petri dish. With a dropper, carefully add drops of water onto the penny. Record the number of drops you can put on the penny before the water begins to drip over the side. 1. What property of water prevents it from overflowing? 2. Which side of the penny holds more water, heads or tails? 3. Add a table spoon of salt to the water and repeat the experiment. Are the results different? Explain why.

PART 2: The USS Paper Clip: Fill a beaker ¾ full of water. Using forceps gently float a paper clip on the surface of the water. 4. What property of water allows it to rest on the water’s surface? 5. Add 2 drops of dish soap to the surface of the water. What happens and why?

PART 3: Varicose Veins in Celery: Observe the celery placed in a beaker of colored water. 6. Describe what is happening? 7. What property of water is being demonstrated? 8. Where else in nature may this phenomenon occur?

PART 4: Paris and Class and Other Things that Do Not Mix: Fill a beaker ¾ full of water. Add 5.0 ml of cooking oil to the beaker. Stir with a stirrer. Observe this mixture as it sits for 4 minutes. 9. Describe what is happening to the oil and try to explain why? 10. What kind of molecule is oil? What kind of molecule is water?

PART 5: I Saw That Salt a Minute Ago: Add a pinch or two of salt to a second beaker filled ¾ full of water. Gently stir and observe. Record what happens to the salt. 11. How is what happened to the salt different than what happened to the oil? Why? 12. Describe this salt & water beaker using the words: solute, solvent, and solution.

ANALYSIS: 13. What is the difference between adhesion and cohesion? 14. How was adhesion demonstrated in this lab activity? 15. How was cohesion demonstrated in this lab activity? 16. Name a substance that will not dissolve in water and explain why. 17. Why is water called the “universal solvent?” 18. What property of water does the water strider (an insect) depend on as it stands and moves across the water’s surface? 19. Water is sticky; give me two everyday examples not used in class. 20. Challenge yourself: When salt is added to water the freezing point decreases. Why?