Magic show or chemistry lab? Sometimes it’s hard to tell the difference! Chemical reactions often produce spectacular color changes that appear to happen just by magic. Now is your chance to put some tricks up your sleeve and wow your friends with scientific sleight of hand.
(Note: Some of the chemicals used in these projects can be hazardous if misused. Use caution when working with chemicals! Read the information on the chemical label before you start, and always wear protective safety equipment such as goggles, gloves, and aprons. Adult supervision required.)
Trick 1 – Confounding Color
Can you get a liquid to change color simply by pouring it into another container?
See this experiment in action before you try it!
* Four flasks, beakers, or drinking glasses
* Universal indicator
What to do:
1. Put 25 drops of universal indicator into the first flask, and then add 200ml of water.
2. In the second flask, put a dropper-full of vinegar.
3. Add a dropper-full of ammonia to the third flask. (Be very careful not to breathe in the strong fumes from the ammonia!)
4. Put 100ml of vinegar in the fourth flask.
5. Slowly pour the contents of the first flask into the second one, then the second into the third and the third into the fourth.
The secret of this magic color change is pH. Chemicals with a low pH (0-6) are acidic, while those with a high pH (8-14) are basic. (A pH of 7 is neutral: neither acidic nor basic.) Universal indicator is a chemical that changes color in the presence of acids and bases from a pH of 2 to 10. Acids turn the indicator red, pink, orange, and yellow, while bases turn it green, blue, and purple. Vinegar is an acid, so when you poured the indicator solution into the second flask, it turned red. Ammonia is a base, so when you mixed the acidic vinegar solution with ammonia, it raised the pH and the water turned blue. If you had enough vinegar in your last flask, the solution should have turned red again. (If it didn’t, try adding a little more vinegar.)
Trick 2 – Mystery Pitcher
Can you pour red “kool-aid” out of a pitcher of water? Try it out and impress your audience – just don’t drink the finished product!
Check out our project video to see this trick in action!
Ngoài ra có thể xem thêm một số video khác như sau: