Boiling.. But No Bubbles?

Have you observed what happens to water when it boils? If you look closely, initially as the water begins to heat up, bubbles will begin to form at the bottom and sides of the vessel. They slowly rise to the surface of the water and pop. When the water is completely on a boil, bubbles vigorously jostle on the surface of the water. Bubbles are essentially a part of the process of boiling - until recently.

Scientists have found a new nano-material that can now repel bubbles.

What causes bubbles?

Bubbles are commonly misunderstood to be "air". In fact it is caused by water that turns into steam when it reaches 100 degrees centigrade. Did you know that if an object is dropped into boiling water, bubbles will stick to it too? Try putting a spoon into a pot of boiling water. (Remember: Never do this without an adult around. It is very dangerous).

 Vapor cushion causing water to levitate

Levitating Bubbles

Boiling water bubbles are actually quite fascinating (from a distance). Have you noticed cooks test the heat of a skillet by sprinkling a few drops of water on it? On a hot pan the drops of water skim along the surface almost as if it were levitating or repelling the surface. This is because, the water bubble dances on a cushion of vapor.

This levitation of water is known as the Ledienfrost effect, named after the scientist Johnn Gottlob Ledienfrost who explored this phenomenon as far back as 1756. When the cushion of vapor collapses, the drop of water will boil explosively as it falls on the hot surface. In fact, the greatest danger of boiling water is the explosion of water bubbles when the vapor layer collapses.

So, what if we can boil water without bubbles? Suppressing the bubbling could help reduce the damage caused by fizzing on surfaces. It can even prevent vapor buildup that can lead to disastrous explosions as in the case of nuclear power plants.

The New Nano-material

Recently scientists managed to boil water without bubbles. A team of scientists collaborated from various locations to develop a super-water-repellant coating made of nano-particles and covered with an organic, hydrophobic compound. (Nanoparticles are particles only nanometers, or billionths of a meter, in size).

In an experiment they conducted on two identical iron balls, one of which was coated with the nanomaterial, they noticed that there was a continuous film of vapor on the ball without bubbling. Watch the video below on how the hydrophobic (water repellant) material behaves in boiling water versus the hydrophilic (having a strong liking for water) material on the left.

By Anitata Ramachandran

From youngzine