Many fruit drinks now advertise that they are fortified with vitamin C. You can do a simple test to see if this is true and to compare which drinks contain the most vitamin C.
Instructions
1. Pour water into the clear plastic cup until it is two-thirds full.
2. Put three drops of iodine into the cup of water.
3. Squirt a little spray starch into the water. It should turn a deep bluish-purple color.
4. Put an effervescent vitamin C tablet into the cup and observe what happens. The solution should turn clear. The vitamin C reduces the colored iodine molecules (made of two iodine atoms) to colorless ions (a single iodine atom).
5. Empty the cup and rinse it out.
6. Repeat the same steps as above: fill with water, add three drops of iodine, then squirt in some spray starch.
7. Add your first test fruit drink one drop at a time, counting how many drops you need to add to turn the solution clear. If it does not eventually turn the solution clear, then the drink does not contain vitamin C.
8. Repeat this experiment for each test drink. You can compare which drinks contain the most vitamin C by comparing the number of drops it took to turn the solution clear. The drinks with the most vitamin C will be those that took the least number of drops to turn the solution clear.
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