Physical Menu |
|
|
Material:1. One can of sodapop.2. A glass container (cafeteria glass, beaker, or erlenmeyer flask). 3. Table salt. 4. Teaspoon 5. Basin (to catch the overflow) |
Film and activity update provided by Heather West |
Procedure:1. Pour the soda into the glass. Try to tip the glass and pour along the side so that the pop doesn't fizz too much.2. Pour about one teaspoon (or more, if you like) of salt into the spoon. 3. Dump the salt into the soda. 4. Watch the fizz rise! |
|
Questions:1. How soluble is salt in water?2. How soluble is gas in water? 3. What happens to the salt when you dump it in the sodapop? 4. What happens to the gas when you dump the salt in the sodapop? 5. Why does the gas dissolve out of the sodapop? 6. How can you apply what you just learned about the solubility of gas in water to aquatic and marine animals? What happens to a fish (or a SCUBA diver) if it moves from a deep area to the surface too quickly?
Rationale:Salt is very soluble in water. Air dissolves in water, but not very well, especially compared to salt. In a solution, the solvent (the water in this case) can only hold so much solute (stuff like salt, sugar, air, etc.) . When the salt is added to the water, the water can't hold as much dissolved air in it, so the air escapes and we see the fizz.Another way to say this is that the solubility of the gas is decreased. The things that affect the solubility of gas in water include temperature, pressure, and the amount of stuff already dissolved in the solution. A cod fish (or a SCUBA diver) swimming deep in the ocean is under a lot of pressure. If a fisher catches the fish and pulls it up quickly, the pressure that the fish is under decreases. Then not as much air can be dissolved in the blood of the fish. The gas in the blood dissolves out, and the fish has a bloated swim bladder and its tummy will be puffed up. Quick changes like this can kill a fish or a diver. Application:SCUBA gear, physiology of marine and aquatic animals, storing sodapop.
|
Physical Menu |
|
|
