Why do things explode?

Hydrogen is a flammable gas. It will react violently with the oxygen in air when ignited. In an enclosed area it can cause an explosion, but if the gasses are not contained, it will just burn and precipitate water. The Hindenberg was filled with hydrogen, but it didn't explode, it burned. There are many, many substances that can explode in the proper situations. Trinitrotolulene (TNT) is a familiar one. Nitroglycerine and ammonium nitrogen triiodide are a couple of others. In the right situation, Uranium or Plutonium will explode in a most convincing manner. That was what was used to make the first atomic bombs.  more