Ammonia is an antipode and analog ... of water?

The smell of this gas is known to everyone - you can immediately feel it if you open the jar with ammonia. Something about his properties we were told at school. It is also known that it is one of the key products of the chemical industry: it is in it that it is easier to turn nitrogen, which so 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, drugs and polymeric materials ...

Brief information

The name of this substance comes from the Greek "hals ammoniakos", which in translation means ammonia. The molecule of ammonia is a kind of pyramid, at the top of which there is a nitrogen atom, and at the base - three hydrogen atoms. The formula for this compound is NH3. Under normal conditions, ammonia is a colorless gas with an asphyxiating, pungent smell. Its density at -33.35 ° C (the boiling point) is 0.681 g / cm ³ . And this substance melts at -77.7 ° С. The molar mass of ammonia is 17 grams per mole. The pressure of 0.9 MPa causes the ammonia to contract at room temperature. It is produced in the industry under pressure by catalytic synthesis from hydrogen and oxygen. Liquid ammonia is a highly concentrated fertilizer, a refrigerant. Care should be taken with this substance, as it is toxic and explosive.

Curious facts

Liquid ammonia has rather unusual properties. Outwardly it resembles simple water. Like H ₂ O, it perfectly dissolves many organic and inorganic compounds. Most salts in it dissociate when dissolved in ions. At the same time, chemical reactions, in contrast to water, occur in it quite differently.

The data in this table lead to the idea that liquid ammonia is a unique medium for carrying out certain exchange reactions that are practically unworkable in aqueous solutions. For example:

2AgCl + Ba (NO ₃ ) ₂ = 2AgNO ₃ + BaCl ₂ .

Since NH ₃ is a strong proton acceptor, acetic acid, despite the fact that it is considered to be weak, will dissociate completely, just as strong acids do. Of greatest interest are solutions in ammonia alcohol of alkali metals. As early as 1864, chemists noticed that if they were given some time, ammonia would evaporate, and in the sediment would be pure metal. Almost the same thing happens with aqueous solutions of salts. The difference is that the alkali metals, although in a small amount, but still react with ammonia, resulting in the formation of salt amides:

2Na + 2NH3 = 2NaNH2 + H2.

The latter are quite stable substances, but when they come into contact with water they immediately disintegrate:

NaNH2 + H20 = NH3 + NaOH.

When studying the properties of liquid ammonia, chemists have drawn attention to the fact that when the metal dissolves in it, the volume of the solution becomes larger. Moreover, its density decreases with this. This is another difference between the solvent in question and ordinary water. It's hard to believe, but the concentrated and diluted solution of any alkali metal in liquid ammonia does not mix, despite the fact that the metal in both of them is the same! Thanks to the experiments, new and surprising facts are constantly being discovered. Thus, it turned out that the sodium solution frozen in liquid ammonia has very little resistance, and therefore NH ₃ can be used to produce 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.