Ammonia is one of the most extensively made chemicals in the United States of America. It is one of the most common hydride present in the atmosphere. The ammonia found in the atmosphere is formed mainly due to the decomposition of bacteria which is released from the nitrogenous elements from animals and plants. The IUPAC name of ammonia is azane. The chemical formula of ammonia is NH3. There are various Properties of Ammonia.
Preparation of Azane:
Small quantities of azane are present in soil and air due to the decay of organic matter which are nitrogenous in the nature.
For small scale production ammonium salts are made to react with caustic soda to obtain ammonia:
2NH4Cl + Ca(OH)2 \(\rightarrow\) 2NH3 + 2H2O + CaCl2
Haber’s process is used for large scale production. Steps involved in Haber’s process are:
N2 (g) + 3H2 (g) ↔ 2NH3 (g)
- Nitrogen and hydrogen are used as raw materials for the reaction. The impurities for the gases are removed by a process called scrubbing.
- After the process scrubbing, the gases are amalgamated together and it is then passed through a compressor. The mixture is then compressed at a pressure of 200 atm.
- The compressed gases are then passed through a converter, where the gases are heated at temperature 450°C and pressure at 200 atm. The nitrogen reacts with hydrogen to form ammonia, however only approximately 15% of the gas is formed.
- The mixture of ammonia, hydrogen and nitrogen is removed from the converter. It is cooled where it liquefies in the tank and hence collected.
Properties of Ammonia:
The Properties Of Ammonia are given as follows-
- Azane is a gas which is colourless in nature and has a pungent smell.
- It boils at 198.4K and 239.7K.
- This gas is highly dissolvable in water. The aqueous solution of NH3 is a weak base as OH- ions are formed.
NH3+H20 → NH4++OH–
- Ammonium salts are formed when it reacts with an acid.
ZnSO4+2NH4OH (g) → Zn(OH)2+(NH4)2SO4
Uses of ammonia:
- Properties of Ammonia in its aqueous state is used as a refrigerant.
- It is used in the manufacturing of Urea .Urea is an excellent fertilizer of nitrogen.
- Azane can be used to remove grease due to its cleansing properties.
Friedrich Wilhelm Ostwald at the start of 20th century developed a process in which ammonia was used to obtain nitric acid. Due to the development of nitric acid, it helped the Germans during the World War Ito make explosives without importing it from other countries like Chile. Chemical formula of nitric acid is HNO3.
Preparation of HNO3:
For small scale preparation this gas is made by heating concentrated sulphuric acid along with NaNO3 or KNO3
NaNO3+H2SO4 → NaHSO4+HNO3
For large scale preparations Ostwald process is used.
In this process, NH3 undergoes catalytic oxidation by oxygen which is present in the atmosphere in the presence of Pt/Rh as a catalyst at 500 K and a pressure of 9 bars.
4NH3+5O2 → 4NO(g)+6H2O
Nitric oxide which is obtained is then made to react with oxygen to form NO2.
2NO+O2 → 2NO2(g)
NO2 formed is dissolved in H2O to form HNO3
3NO2 (g)+H2O(l) → 2HNO3(aq)+NO(g)
Properties of HNO3
- It is colourless in nature.
- The boiling point of the liquid is 84.1°C and it freezes at -41.55 °C to form a white solid.
- It acts as a strong acid which dissociates to form nitrate ion and hydronium.
HNO3 (aq) +H2O (l) → H3O+(aq)+NO3–(aq)
- HNO3 in its concentrated state acts a strong oxidising state
Cu+4HNO3 → Cu(NO3)2+ 2NO2+2H2O