Welcome to another naughty post! If you survived yesterday's prank, check what I got for you today...
How about letters that disappear from paper? Do you want to make your friends think they've lost a whole project or do you just want to write secret messages? Ink that disappears is the ideal solution for you!
(Image source: pixabay.com)
Materials
- 0.10 g thymolphthalein for blue ink or phenolphthalein for red ink (1/3 of 1/8 tsp)
- 10 ml (2 tsp) ethyl alcohol (ethanol - C2H6O) [can substitute 14 ml or 3 tsp of ethyl rubbing alcohol]
- 90 ml water
- 20 drops of 3M sodium hydroxide solution or 10 drops 6M sodium hydroxide solution [make a 3M sodium hydroxide solution by dissolving 12 g of sodium hydroxide NaOH (1 level tablespoon of lye) in 100 ml (1/2 cup) of water.]
Cautions
For your own safety be very careful when handling the sodium hydroxide solution because the base is really caustic. Gloves should be used to protect your skin.
Never spray the ink on somebody's skin or eyes.
This is supposed to be fun, we don't want anyone to get hurt.
Steps
- Dissolve the thymolphthalein/phenolphthalein in the ethyl alcohol.
- Add the water (you'll get a milky solution).
- Add sodium hydroxide solution drop by drop until you get a dark blue or red solution (it might take a little more or less than the 20 drops we mentioned above).
- Use some fabric to test the ink for faster results, the interaction with air is less over paper so it will need more time.
- A few seconds later the stain will vanish. The initial pH of the ink is about 10-11 (you need to be cautious). When it's exposed to the air it drops to 5-6. There may be some leftover stains on dark cloth but they will wash away.
- Now pick your victim and have them write something for you, ask them to help you with an assignment, shopping list or something. When the text is ready just wait... (as we said, it takes longer on paper)
- When the letters disappear it's time to start wondering where did a whole text go and break the news to your friend.
- To make the ink come back brush the cloth with a cotton ball dipped in ammonia.
- Keep the rest of the ink in a sealed container (You can dispose off down the drain if you don't want it anymore).
And the science behind it
Ink that disappears is basically a water-based pH indicator (do you remember when we talked about acids and bases?). The basic indicator (10-11 initial pH) turns to acidic (5-6 pH) after exposed to air.
When we apply the ink, the water from the solution reacts with the carbon dioxide (CO2) in the air and produces carbonic acid:
CO2 + H2O = H2CO3
The acid, in turn, reacts with the sodium hydroxide and forms sodium carbonate and water. The neutralization of the base causes the change of the indicator color and so the ink vanishes:
2 Na(OH) + H2CO3 = Na2CO3 + 2 H2O
References
thoughtco.com-How_to_make_disappearing_ink
Thank you for stopping by and giving this post a read. I hope you enjoyed it! If you please, feel free to pay a visit to my blog and check out my short stories along with plenty of educational posts and of course my bizarre natural phenomena series.
Special thanks and mentions go to:
Until my next post,
Steem on and keep smiling, people!