The Landolt Clock Reaction

By Anupum Pant

Steve Spangler Never ceases to amaze me. Once again I found this old video of him on the Ellen show. These are a few experiments he does on the stage…

  • Lights a tube light with his bare hands and Ellen’s.
  • A transparent liquid suddenly instantly changes colour.
  • Blows the hydrogen and oxygen mixture on Ellen’s hand.
  • And makes someone from the audience walk across the table on a non newtonian fluid.

Steve doesn’t exactly explains what happens there, but the second experiment is my favourite. It is the one in which he asks Ellen to pour two transparent liquids into each other and mix them well. Then Ellen waits for a few seconds and the liquid instantly turns into an ink like colour.

The magical effect is actually a chemical reaction known as the Landolt Clock Reaction. It actually involves 3 different solutions (read about them). The reaction happens quicker once the mixing starts and leads to a third reaction which happens immeasurably fast. It’s totally instantaneous and thus the transparent solutions turn into a bluish black iodine starch complex. As steve’s website puts it…

The sudden change from a colorless solution to the blue-black solution is the result of four sequential reactions. First, the bisulfite ions (HSO3-) reduce some of the iodate ions (IO3-) to form iodide ions (I-). Next, the iodide ions (I-) are oxidized by the remaining iodate ions (IO3-) to form triiodide ions (I3-). The solution now consists of triiodide ions (I3-) and soluble starch. In the third reaction, the triiodide ions (I3-) get reduced by the bisulfite ions (HSO3-) to become iodide ions (I-). That continues until all of the bisulfite has been consumed. Finally, the triiodide ions and starch combine to form the dark blue-black starch complex that looks like ink.

See more at: SteveSpanglerScience

Hot Ice

By Anupum Pant

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For years we’ve been subconsciously conditioned to think of something cool when the word ‘ice’ is heard. But, does ice always has to be cool? How much more interesting, than water-ice, can ice be?

What is it?

The name: Hot ice isn’t solidified water, it isn’t anything even close to water. Neither is hot ice, hot. It is just a common name for Sodium Acetate Trihydrate. At room temperature, this substance looks like ice crystals and if heated, it starts turning into a transparent liquid. Since, the ice like crystals are formed at a relatively hotter temperature than water-ice, it is called hot ice.

Everything freezes. While metals ‘freeze’ at extremely high temperatures and carbon dioxide freezes at extremely low temperature, Sodium acetate freezes at 54 degrees centigrade. But, that is hardly anything interesting about it. There is more.

Touch water and turn it to ice

Think about water: Cooling water, beyond its freezing point without it getting solidified, can be done and it is called ‘super-cooling‘. This can be done by not letting water (distilled water) find any ‘nucleation points’ or simply by using an extremely clean tray to freeze it. Now, water remains in a liquid state despite being cooled under 0 degree centigrade. At such a state, if water is disturbed, say using your finger, a chain reaction starts and the water freezes almost instantly. But, doing it is tough.

Making hot ice at home – The same thing that happens with super-cooled water, can happen with sodium acetate. Touch the liquid sodium acetate and it magically turns to ice, it is indeed a fascinating process to watch (watch in the video below). And can be done fairly easily. Moreover, you are not at a danger of getting poisoned in any way. This is the reason it is used to make hot ice. It can be made at home using vinegar, baking soda and a steel vessel.