The smell of gas is known to everyone - you can feel it immediately when you open a jar with ammonia.Something about its properties, we were told in school.It is also known, and the fact that he is one of the key products of the chemical industry: it is easier to turn nitrogen, which does not like to enter into chemical reactions.Ammonia - the first paragraph, which begins production of many nitrogen compounds: a variety of nitrite and nitrate, explosives and aniline dyes, pharmaceuticals and plastics ...
Background
name of the substance is derived from the Greek «hals ammoniakos», thatIt translates as ammonia.Ammonia molecule is a kind of pyramid, in the top of which is a nitrogen atom and at the base - three hydrogen atoms.The formula of this compound - NH3.Under normal conditions, ammonia - a colorless gas with a suffocating pungent odor.Its density at -33.35 ° C (boiling point) is 0.681 g / cm3.A melted substance is at -77.7 ° C.The molar mass of ammonia is equal to 17 grams per mole.The pressure of 0.9 MPa at room temperature causes the ammonia to shrink.Prepared in industry it under pressure via catalytic synthesis of hydrogen and oxygen.Liquid ammonia - a highly concentrated fertilizer, refrigerant.With this material should be careful, because it is toxic and explosive.
Interesting facts
Liquid ammonia has a rather unusual properties.Outwardly, it resembles a plain water.Similarly H2O it perfectly dissolves many organic and inorganic compounds.Most salts therein dissociate into ions when dissolved.At the same time, chemical reactions, unlike water, it occurs very differently.
| ZnCl2 | BaCl2 | KCl | NaCl | KI | Ba (NO3) 2 | AgI | ||
|
Solubility at 20 ° C per 100 grams of solvent | ammonia | 0 | 0 | 0.04 | 3 | 182 | 97 |
207 |
| water | 367 | 36 | 34 | 36 | 144 | 9 | 0 |
The data in this table leads to the idea that liquid ammonia - a unique environment for certain metabolic reactions, which in aqueous solutions are not feasible.For example:
2AgCl + Ba (NO3) 2 = 2AgNO3 + BaCl2.
Since NH3 is a strong proton acceptor, acetic acid, although it is considered weak prodissotsiiruet entirely, just as do the strong acid.Of particular interest are solutions in liquid ammonia, alkali metal.Even in 1864, chemists have noticed that if you give them some time, the ammonia evaporates, and in the sediment would be a pure metal.Almost the same thing happens with aqueous salt solutions.The difference is that the alkali metals, even in small quantities, but nevertheless react with ammonia, resulting in formation of salt-like amides:
2Na + 2NH3 + H2 = 2NaNH2.
latter are very stable substance, but in contact with water immediately collapses:
NaNH2 + H2O = NH3 + NaOH.
In the study of the properties of liquid ammonia chemists have noticed that when dissolved metals in it, the solution volume becomes larger.Moreover, its density is lowered.This is another difference between the considered solvent from ordinary water.It is difficult to believe, but the concentrated and diluted solution of any alkali metal in liquid ammonia are not mixed with each other, despite the fact that the metal in both of them the same!Through experiments constantly found new amazing facts.Thus, it was found that frozen in liquid ammonia solution of sodium is very small resistance, and hence, NH3 can be used to produce superconducting system.It is not surprising that this gas and its solutions are still interested in the minds of both physicists and chemists.
