How is hydrogen a flammable gas

Topic 8 hydrogen explosion

SEND DATESat, April 20, 2019 | 9:45 am | SWR television

Hydrogen is the most common element in the universe. Measured by the number of atoms, it is also the most common in the human body. It is part of water and almost all organic compounds. Thus, bound hydrogen occurs in all living organisms. But hydrogen is also an excellent energy carrier. 1 kilogram of hydrogen contains as much energy as 2.7 kilograms of gasoline.

And what energy hydrogen can develop when it mixes with oxygen, we show in a spectacular experiment:

Five oil barrels, which are open at the bottom, stand next to each other. The barrels are filled with hydrogen. There is a hole in the lid that is still closed. A flammable paste is applied to each hole and an igniter that can be remotely controlled. The barrels are placed on wooden sticks so that air can get into the barrel. As soon as the holes are open at the top, the escaping hydrogen is ignited, it burns and air and thus also oxygen is sucked into the barrels from below. As soon as the hydrogen is enriched with sufficient oxygen, the mixture ignites on the burning flame and lets the barrels fly like a rocket into the air.

This reaction is also known as an oxyhydrogen sample from chemistry class.
The oxyhydrogen reaction is a detonation-like reaction between hydrogen and oxygen and runs at a detonation speed of 2820 m / s, which corresponds to over 10,000 km / h. The detonation in the barrels is mainly directed downwards because the barrels are open at the bottom and there is the least resistance there. This will throw the barrel upwards.
Quite a violent reaction.

This reaction is also used for completely different, useful purposes. For example in engines. Hydrogen is injected directly or indirectly into the engine's combustion chambers and mixed with the air that is drawn in. Oxyhydrogen is produced, which is then ignited and ultimately leads to an explosion. This explosion then drives the piston in the engine. For years, however, hydrogen has also been used as a rocket fuel for flights into space.
But hydrogen is also converted into clean energy in fuel cells. In many German cities public buses that run on hydrogen are already in use. In principle, the same thing happens in a fuel cell as in our experiment, only that the reaction is controlled. In the fuel cell, one speaks of cold combustion. The energy in hydrogen is converted into electricity and heat, and water is produced as a waste product.

Status: April 12, 2017, 11.28 a.m.