Question
Sat November 26, 2011 By: Ayush Singh
 

Explain the properties of ammonia and nitric acid with ALL OF their respective reactions .PLS GIVE DETAILED EXPLANATION.

Expert Reply
Sun November 27, 2011
Ammonia
Ammonia is a chemical consisting of one atom of nitrogen and three atoms of hydrogen. It is designated in chemical notation as NH3.
Ammonia is extremely soluble in water and is frequently used as a water solution called aqua ammonia. Ammonia chemically combines with water to form ammonium hydroxide. 
 

 Ammonia also self-ionizes, although less so than does water.

2NH3 ? NH4+ + NH2-

Ammonia reacts with sodium hypochlorite to form hydrazine.

This is known as Raschig process.

2NH3 + NaOCl ? N2H4 + NaCl + H2O

The combustion of ammonia proceeds with difficulty. However,  yields nitrogen gas and water as products.

4NH3 + 3O2 + heat ? 2N2 + 6H2O

However, with the use of a catalyst and under the correct conditions of temperature, ammonia reacts with oxygen to produce nitric oxide, NO, which is oxidized to nitrogen dioxide, NO2, and is used in the industrial synthesis of nitric acid.

Ammonia readily dissolves in water with the liberation of heat.

NH3 + H2O ? NH4+ + OH?

These aqueous solutions of ammonia are basic and are sometimes called solutions of ammonium hydroxide (NH4OH).

Liquid ammonia is used extensively as a nonaqueous solvent.

 The alkali metals as well as the heavier alkaline-earth metals and even some inner transition metals dissolve in liquid ammonia, producing blue solutions. Physical measurements, including electrical-conductivity studies, provide evidence that this blue colour and  electrical current are due to the solvated electron.

metal (dispersed) ? metal(NH3)x ? M+(NH3)x + e?(NH3)y

These solutions are excellent sources of electrons for reducing other chemical species. As the concentration of dissolved metal increases, the solution becomes a deeper blue in colour and finally changes to a copper-coloured solution with a metallic luster. The electrical conductivity decreases, and there is evidence that the solvated electrons associate to form electron pairs.

2e?(NH3)y ? e2(NH3)y

 

Nitric acid

Nitric acid decomposes into water, nitrogen dioxide, and oxygen, forming a brownish yellow solution. It is a strong acid, completely ionized into hydronium (H3O+) and nitrate (NO3?) ions in aqueous solution, and a powerful oxidizing agent (one that acts as electron acceptor in oxidation-reduction reactions).

4 HNO3 ? 2 H2O + 4 NO2 + O2

Among the many important reactions of nitric acid are: neutralization with ammonia to form ammonium nitrate, a major component of fertilizers; nitration of glycerol and toluene, forming the explosives nitroglycerin and trinitrotoluene, respectively; preparation of nitrocellulose; and oxidation of metals to the corresponding oxides or nitrates.

Strongly electropositive metals, such as magnesium react with nitric acid as with other acids, reducing the hydrogen ion.

Mg + 2 H+ ? Mg2+ + H2

With less electropositive metals the products depend on temperature and the acid concentration. For example, copper reacts with dilute nitric acid at ambient temperatures with a 3:8 stoichiometry.

3 Cu + 8 HNO3 ? 3 Cu2+ + 2 NO + 4 H2O + 6 NO3-

The nitric oxide produced may react with atmospheric oxygen to give nitrogen dioxide. With more concentrated nitric acid, nitrogen dioxide is produced directly in a reaction with 1:4 stoichiometry.

Cu + 4 H+ + 2 NO3? ? Cu2+ + 2 NO2 + 2 H2O

Reaction with non-metallic elements, with the exceptions of nitrogen, oxygen, noble gases, silicon and halogens, usually oxidizes them to their highest oxidation states as acids with the formation of nitrogen dioxide for concentrated acid and nitric oxide for dilute acid.

C + 4 HNO3 ? CO2 + 4 NO2 + 2 H2O

 

 

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