Carbon

Ammonia is a compound of nitrogen and hydrogen with the formula NH₃. It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or indirectly, is also a building block for the synthesis of many pharmaceuticals. Although in wide use, ammonia is both caustic and hazardous. In 2006, worldwide production was

boron ← carbon → nitrogen
- ↑ C ↓ Si	6C Periodic table

estimated at 146.5 million tons.^[4] It is used in commercial cleaning products.

Ammonia, as used commercially, is often called anhydrous ammonia. This term emphasizes the absence of water in the material. Because NH₃ boils at −33.34 °C, the liquid must be stored under high pressure or at low temperature. Its heat of vapourization is, however, sufficiently high so that NH₃ can be readily handled in ordinary beakers, in a fume hood (i.e., if it is already a liquid it will not boil readily). "Household ammonia" or "ammonium hydroxide" is a solution of NH₃ in water. The strength of such solutions is measured in units of baume (density), with 26 degrees baume (about 30 weight percent ammonia at 15.5 °C) being the typical high concentration commercial product.^[5] Household ammonia ranges in concentration from 5 to 10 weight percent ammonia.