What's the difference between a hydrogen explosion and an oxygen explosion? Quite a lot. Take a look at this succession of exploded balloons, and compare the booms.

Oxygen, being present at many explosions, has gained a rather bad reputation. Some people think that oxygen is explosive. As we can see in this experiment, oxygen, while not being completely innocent, is no more than an accessory. Burning is the removal of oxygen from the area surrounding a burning object, and the addition of it to whatever is being burned. A fire can't get started without oxygen around. But oxygen itself is completely harmless. As the gentleman with the extension-torch (which I covet, by the way), moves from one balloon to the next, he demonstrates the explosive capacity of hydrogen, oxygen, and hydrogen and oxygen.

The oxygen, explosion-wise, is a real let-down. Without anything to burn, it's about as impressive a pop as can be produced with a pin. That being said, it's rare that there is an environment in which oxygen has nothing to burn. But even with burnable material on hand, a lot of oxygen (like all the oxygen in the room) is useless unless it's pressed right up against the thing that is meant to burn. There is an impressive explosion when the balloon filled with hydrogen goes up. In fact, one of the reasons it's so impressive is we're able to see it. It takes time for the hydrogen in the pure hydrogen balloon to mix with the oxygen in the air, and that times lets us see a brief, beautiful, spread of fire.

When the balloon filled with both hydrogen and oxygen goes up (and incidentally, the best mix of the two will include between 71 and 80 percent hydrogen) the explosion goes so fast that, for a moment, it looks like someone sped the tape up while creating a sonic boom right next to our ear. The oxygen is already where it needs to be to ignite the hydrogen, and it does so so quickly that we actually miss the explosion.

Incidentally, the hydrogen and the oxygen combine to form the famous H2O. This experiment uses fire to create water.

[ Via Rutgers and UC Berkeley.]