The smell of this gas is known to everyone - you can immediately feel it if you open a jar of ammonia. We were told something about its properties at school. It is also known that it is one of the key products of the chemical industry: it is the easiest way to turn nitrogen into it, which does not like to enter into chemical reactions. Ammonia is the first point from which the production of many nitrogen-containing compounds begins: various nitrites and nitrates, explosives and aniline dyes, medicines and polymeric materials…
Quick reference
The name of this substance comes from the Greek "hals ammoniakos", which means ammonia. The ammonia molecule is a kind of pyramid, at the top of which there is a nitrogen atom, and at the base there are three hydrogen atoms. The formula of this compound is NH3. Under normal conditions, ammonia is a colorless gas with a suffocating, pungent odor. Its density at -33.35 °C (boiling point) is 0.681g/cm3. And this substance melts at -77.7 ° C. The molar mass of ammonia is 17 grams per mole. A pressure of 0.9 MPa causes ammonia to shrink at room temperature. It is obtained in industry under pressure using catalytic synthesis from hydrogen and oxygen. Liquid ammonia is a highly concentrated fertilizer, a refrigerant. Care must be taken with this substance as it is toxic and explosive.
Curious facts
Liquid ammonia has rather unusual properties. Outwardly, it resembles plain water. Like H2O, it perfectly dissolves many organic and inorganic compounds. Most of the s alts in it dissociate into ions when dissolved. At the same time, chemical reactions, unlike water, take place in it in a completely different way.
| ZnCl2 | BaCl2 | KCl | NaCl | KI | Ba(NO3)2 | AgI | ||
| Solubility at 20˚C based on 100 g of solvent | ammonia | 0 | 0 | 0.04 | 3 | 182 | 97 | 207 |
| water | 367 | 36 | 34 | 36 | 144 | 9 | 0 | |
Data in thisThe table leads to the idea that liquid ammonia is a unique medium for carrying out some exchange reactions that are practically impossible in aqueous solutions.
For example:
2AgCl + Ba(NO3)2=2AgNO3 + BaCl 2.
Because NH3 is a strong proton acceptor, acetic acid, despite being considered weak, will dissociate completely, just as strong acids do. Of greatest interest are solutions in ammonia of alkali metals. Back in 1864, chemists noticed that if you give them some time, the ammonia will evaporate, and the precipitate will be pure metal. Almost the same thing happens with aqueous solutions of s alts. The difference is that alkali metals, although in small quantities, still react with ammonia, resulting in the formation of s alt-like amides:
2Na+ 2NH3=2NaNH2 + H2.
The latter are quite stable substances, but upon contact with water they immediately disintegrate:
NaNH2 + H2O=NH3 + NaOH.
When studying the properties of liquid ammonia, chemists noticed that when the metal is dissolved in it, the volume of the solution becomes larger. Moreover, its density decreases. This is another difference between the solvent in question and ordinary water. It's hard to believe, but a concentrated and dilute solution of any alkali metal inliquid ammonia do not mix with each other, despite the fact that the metal in both of them is the same! Through experimentation, new amazing facts are constantly being discovered. So, it turned out that a sodium solution frozen in liquid ammonia has a very low resistance, which means that NH3 can be used to obtain a superconducting system. It is not surprising that this gas and its solutions are still of interest to the minds of both physicists and chemists.
