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

The Potato Puzzle

By Anupum Pant

Some call it the Potato paradox, but I prefer calling it a puzzle. It isn’t really a paradox. It’s just that we tend to get confused easily when working with such problems and most times end up with the wrong answer. Here’s the question:

You have 100 kg of potatoes. Assume that they are made up of 99% water. Now, you keep them outside to dry for a while. When measured for water content now, they contain 98% water. What do you think is the weight of these dried potatoes now?

Answer quickly first. Then, try and calculate. It isn’t really tough.

Take 15 minutes, or more if you have to. Use papers, pens and calculators if you have to. But whatever you do, stay honest. Don’t search for the solution on the internet, or don’t read further if you haven’t done it yet. Trust me, your brain won’t like the answer.

Solution – [Wikipedia]

The answer is: 50 kg.

For the explanation, watch this visual explanation…

The Evil Lunar Dust

By Anupum Pant

Space exploration is a tough job. Besides a myriad of challenges that have to be dealt with, space equipment and astronauts travelling to places like the moon or mars, have to deal with a peculiarly wicked foe – The dust.

This isn’t the kind of normal dust we deal with here on earth. ‘Downright evil’ is the phrase that describes the dust on moon! We may not realize it, but lunar dust is a filthy thing and causes a lot of problems. Of course, the dust on mars is no better.

Back in 1972

For instance, let us see how moon dust makes things complicated for engineers and astronauts.

Most of the upper surface of the moon is covered with a mixture of loose material comprising of dust, soil, rocks and pebbles (and other random stuff too). Normally, at places, this layer of mixture ranges from 4 to 6 meters in thickness.

The fine part of this mixture is called the lunar soil and is significantly different from the soil found on earth. It is present almost everywhere on the surface of the moon and is a result of breaking of rocks into small particles by meteorite and micrometeorite impacts; also there is no wind and rain to soften the pieces. This is the part of that loose stuff which is known for causing immense troubles.

The dust is super-fine and extremely hard. You can think of it as collection of little shards of glass. Despite being completely dry, it sticks to everything it touches and as it is super-fine, it can get into tiny creases. If inhaled, it can be toxic; like millions of tiny sharp shards piercing into the inner walls of your respiratory system. A tiny amount of it can eventually kill a full grown man.

Back in 1972, the Apollo 17’s crew learnt this as soon as they stepped out. The dust started clogging their air vents and started dropping the pressure. When returning to their space capsule, Jack Schmitt and Eugene Cernan forgot to brush off the dust. They were stuck with it for the whole time during their journey back home. Some of the dust went airborne in the craft and Schmitt started complaining of congestion. Fortunately, the amount was too small to hurt them a lot. Soon the symptoms subsided and space agencies learnt a lesson – Find a way to deal with the lunar dust.

On mars: Dust on mars can travel places due to dust storms and cause more problems.


Scientists at NASA found a great way to deal with this dust using an electric zap. They were able to develop electrical fields which can clear about 99% of the dust from the equipment. These dust shields will be tried on in the year 2016.