By now, most people watching the news know about the massive explosions at a Texas fertilizer plant.
The main chemical in fertilizer, ammonium nitrate, is particularly nasty stuff. Nitrates are themselves partial to exploding: Both TNT and gunpowder have NO3 groups that tend to react violently and rapidly. However, the ammonium (NH4+) part is also quite nasty, particularly when it is in the form of its neutral compound, NH3 (i.e. anhydrous ammonia).
When most people think “ammonia,” they think of the liquid (& aqueous) solution of ammonia, which is just ammonium hydroxide. Anhydrous ammonia is far, far nastier. It is a liquid at very low temperatures or under pressure, so its gaseous nature can create clouds of ammonia. It is reported that the fertilizer plant had just gotten in about 200 tons of anhydrous ammonia. Ammonia can cause blindness and even cessation of breathing. Far beyond the explosion itself, it is the leak of ammonia gas that caused such an extensive evacuation of the town of West, Texas.
In fact, it is now being reported that the blast was initiated by a single train car of ammonium nitrate. To underscore just how powerful this compound can be, one of the subsequent explosions was recorded and can be see below:
Whether this is just an accident, or criminal in nature, remains to be seen. Ultimately, caution when using this, or other, dangerous chemicals ought to always be paramount.