"More kitchen messes"
DO any 3 of the following experiments:
Here are the materials you need to do them, by experiment number:
Experiment #1: Jar, Sandwich baggie, tape or rubber band.
Experiment #2: 1.5 cups of cornstarch, water, measuring cup.
Experiment #3: Cooking oil, water, dish soap, stirrer, a glass.
Experiment #4: Ice cubes, salt, sewing thread, a glass or mug.
Take a plastic sandwich bag, tape, or rubber band-it so that it surrounds a jar (like a pickle jar, or a bottle, etc). Before taping the bag to the jar, make sure it has some air in it. Now, see if you can push the bag into the jar.
(note: a GOOD way to avoid a major mess is to make this stuff in a ziploc or plastic bag)
Pour 1.5 cups of pure cornstarch slowly, while stirring into a plastic mixing bowl containing 1 cup of water. The mixture will get more viscous as more cornstarch is added. Slowly stick your finger into the white blob. Slam your fist down into the mixture. What happens when you apply pressure to the mixture? [Your finger will pass easily through the mixture when slow gentle pressure is applied. When much greater pressure is applied by slamming your fist into a pan of it, there is great resistance offered. In other words, the viscosity increases when subjected to greater pressure.] Roll some of the mixture up into a ball and set it on the table. Observe what happens.
(1)Fill a beaker sized jar, or glass about half full with water and then pour about half of that volume (half as much as there was of water) of cooking oil over the water. Observe what happens.
(2) Now, stir-up the oil and water, and leave it alone for a while, and observe what happens. (rest of this experiment on back side)
(3)Now add a few squirts of liquid dish detergent and vigorously stir the mixture. After mixing, leave the jar alone, and see what happens. If the mixture is doing what it did in step 2, then try adding a few more squirts of dish detergent, stir again, and see what happens.
(1)Float an ice cube at the top of a cup of cold water that is full to the brim.
(2) Get around 20 cm of sewing thread.
(3) Shake some salt onto the ice cube in the glass.
(4) Rest the thread on this salty cube of ice and let thread hang over side of glass.
(5) Wait about a minute. Then, slowly, lift the thread.
(6) If nothing happens, try again, this time waiting a little longer before lifting the thread.
Questions from your kitchen experiments.
1A: What property of matter was this little experiment demonstrating?
1B: What was keeping the bag from going into the jar/container?
1C:How could one get the bag to go into the jar without making a hole in it? (Hint: think about how you can change the volume of a gas)
2A: What are the three common phases of matter called? Include descriptions of the characteristics of each of these three phases of matter.
2B: What two phases of matter were combined to make this "stuff"?
2C: Among the three phases of matter, where would you classify this "stuff"? Be sure to back your classification with observations you made of this stuff.
3A. Compare the densities of the water and the oil.
3B. Is the oil and the water in the container (without any stirring or detergent) considered a mixture? (look up the scientific definition for mixture)
3C. Was the mixture that you made at any stage in this experiment considered a solution? What is a solute? What is a solvent?
4A.Which would freeze first, an ice cube tray with fresh water, or an ice cube tray with very salty water? If you're not sure, try it.
4B. Why do snowplows drop salt on the roads in the winter? What is the salt doing?
4C. What is the melting point of ice water? What does salt does to this melting point? What did you witness that supports your answer?