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?
What You Need:
- Four flasks, beakers, or drinking glasses
- Universal indicator
What You Do:
- Put 25 drops of universal indicator into the first flask, and then add 200ml of water.
- In the second flask, put a dropper-full of vinegar.
- Add a dropper-full of ammonia to the third flask. (Be very careful not to breathe in the strong fumes from the ammonia!)
- Put 100ml of vinegar in the fourth flask.
- 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!
What You Need:
- Phenolphthalein solution
- Sodium carbonate
- 5 glasses and a non-see-through pitcher of water
What You Do:
- In the first glass put a little less than 1/8 teaspoon of sodium carbonate, in the second put 6 drops of phenolphthalein solution, and in the third put three droppers-full of vinegar.
- Add a few drops of water to the first glass and stir to dissolve the sodium carbonate.
- Fill all the glasses with water from the pitcher, then pour all of them back in the pitcher except for the glass with vinegar.
- Refill the remaining four glasses – the water will be red!
- Now pour all five glasses back in the pitcher. Refill the glasses one last time — the liquid will be colorless again!
Like the universal indicator, phenolphthalein is a pH indicator, but it only turns colors in reaction to bases. When you poured the four glasses back into the pitcher, the phenolphthalein reacted to the sodium carbonate, a base, and turned the solution to red “kool-aid.” To change it back to “water,” all you had to do was add the acidic vinegar, which turned the phenolphthalein colorless again.