How Helium Works Essay, Research Paper

How Helium Balloons Work

There is something incredibly special about helium balloons! If you buy one at the circus or fair, you can hold its string and it will ride along above you. If you let go of the string it will fly away until you cannot see it anymore. If you have ever wondered why it flies away, the passages below can help you to figure out the mystery.

Helium floatation

Helium balloons work using exactly the same law of buoyancy. In this case, the helium balloon that you hold by a string is floating in a “pool” of air. The helium balloon displaces an amount of air (just like a empty bottle displaces an amount of water). As long as the helium plus the balloon is lighter than the air it displaces, the balloon will float in the air. It turns out that helium is a lot lighter than air. The difference is not as great as it is between water and air (a liter of water weighs about 1,000grams, while a liter of air weighs about a gram), but it is significant. Helium weighs 0.1785 grams per liter. Nitrogen weighs 1.2506 grams per liter, and since nitrogen makes up about 80% of the air we breath, 1.25 grams is a good approximation for the weight of liter of air. Therefore, if you were to fill a one-liter soda bottle full of helium, the bottle would weigh about 1 gram less than the same

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bottle filled with air. That doesn’t sound like much – since the bottle weighs more than a gram the bottle will not float. However, in large volumes, the 1-gram per liter difference between air and helium can really add up. This explains why balloons are generally quite large – they have to displace a lot of air to float.

So why is helium so much lighter than air? It’s because helium atoms are lighter than a nitrogen atom. It has fewer electrons, protons and neutrons than nitrogen atoms do, and that makes it much more lighter. Approximately the same number of atoms of each of the elements fills approximately the same amount of space. Therefore, the gases made of lighter atoms are lighter.

If you put helium in a balloon and let go of the balloon, the balloon rises until it pops. When it pops, the helium that escapes has no reason to stop – it just keeps going and leaks out into space. Therefore, in the atmosphere there is very little helium at any given time. The helium comes from alpha particles emitted by radioactive decay. Since the decay of uranium emits lots of alpha particles and a natural gas pocket tends to be a sealed container underground. Helium is then carefully distilled out of natural gas to produce the helium we put in balloons. Helium is safe for balloons pumping because it is a very stable gas (Noble Gas). However, since the cost of extraction of helium is so expensive, this explains why a helium air balloon costs you quite a fortune when you buy it.