0923A

Our trip to Science Centre lets us understand more about the fantastic experiments that revolves around Chemistry. The experiments shown to us consist of the invisible ink, elephant toothpaste, silver mirror, dragon fire, super absorbent polymer and many more. The experiment which impresses us is the Invisible Ink.
DIY Invisible Ink
• Use the juice of an orange/ lemon to write some words
• Use a warm iron to heat up the paper
• The words written in the juice can now be seen
Reactants used: Potassium thiocyanate[KSCN] & Ferric chloride[FeCl3]

Equation:
KSCN(aq) + FeCl3(aq) -> [Fe (SCN)]^2+(aq)
Colourless Brick red light red

Applications
1) Making an Invisible Ink Pen
• Pour lemon juice into your ink well or small bowl. Vinegar also works as a less effective alternative.
• Try a cotton swab, a toothpick, fountain pen, or calligraphy pen. Dip it into the invisible ink.
Write your message.
• Draw a map to your secret treasure, write a love letter, or put the combination to your vault on the back of your business card.
• Allow the ink to dry. As the ink dries your message will disappear.
• To reveal your secret message. Heat the invisible ink to reveal your message.
• Try holding your message over a light bulb, ironing the message, placing it on a cookie sheet in a hot oven for a few minutes or holding it around 4 inches above a flame. The ink will allow the written message to burn faster than the paper, turning your secret message brown.
• Stop heating before your paper scorches.

How To Make Invisible Ink For Secret Spy Messages DIY - The most amazing bloopers are here
2) Making an Invisible Ink printer
Lemon juice has been used as invisible ink for centuries thus; messages written in lemon juice are invisible to the naked eye. However, when brushed with a mix of iodine and water, they become quite visible. An updated version of this technique is by modifying an
HP ink cartridge so that it prints in lemon juice instead of ink.


Fill a Used Print Cartridge with Invisible Ink - video powered by Metacafe
Other Invisible Inks
• Phenolphthalein, commonly used as a pH indicator, turns pink in the presence of a base such as ammonia fumes or sodium carbonate.
• Vinegar, is revealed by red cabbage water. Vinegar contains acetic acid that affects the pH indicator in red cabbage water. Vinegar may also be developed by heat, as above.
• Ammonia, developed by red cabbage water.
• Copper sulfate, developed by sodium iodide, sodium carbonate ammonium hydroxide or potassium ferricyanide.
• Lead(II) nitrate, developed by sodium iodide.
• Iron sulfate, developed by sodium carbonate or potassium ferricyanate.
• Cobalt chloride, developed by potassium ferricyanide.
• Iron sulfate, developed by sodium sulfide.
• Starch, developed by iodine solution which turns starch dark blue and the paper light blue.
• Lemon juice, developed by iodine solution (ink turns white, paper turns light blue).
• Sodium chloride (common table salt), developed by silver nitrate.

Done by: Lan, Melissa, Huong ,Theora, Yong Bang (0923A)