There are a number of the acid uses in industry. One of the biggest uses of Nirtic Acid is in the fertiliser industry. All nitrates are soluble and the reaction between Ammonia and Nitric Acid generates Ammonium Nitrate. This can either be dissolved in water before application or spread as a powder on the land for the rain to dissolve. The chemical formula for this reaction is:-
NH3 + HNO3 > NH4NO3
Since plants require a source of Nitrogen for the production of proteins to develop and grow, the more Nitrogen available to the plant the better it will grow and the higher yield the crop. Nitric Acic is still widely used in the production of explosives such as TNT (tri-Nitro Toluene) and Nitroglycerine. These are used as explosives since they decompose to a large volume of gas on ignition. TNT is produced in a three step nitration process with increasingly more forcing conditions.
Stage 1 involves:-
C6H5CH3 + HNO3 > C6H4NO2CH3
(where the reaction takes place in the presence of Sulphuric Acid)
Stage 2 involves:-
C6H4NO2CH3 + HNO3 > C6H3(NO2)2CH3
Stage 3 involves:-
C6H3(NO2)2CH3 + HNO3 > C6H2(NO2)3CH3
(where the reaction takes place in the presence of Oleum)
Nitroglycerine is produced by adding Glycerine slowly to a colled mixture of Oleum and Nitric Acid. the acid uses also include purification of metals. Since the acid is such a strong oxidiser, it is very efficient in the purification of metals from their respective ores and also as part of liquid fuel rockets.
A Nitric solution of approximately 10% Nitric Acid in water is often used to artificially 'age' maple or pine furniture. This process produces a 'grey-gold' colour to the wood that is not dissimilar to the aged colour of waxed or oil-treated wood.
There are a number of other Nitric Acid uses in the laboratory, one of the most common being a mixture of the acid with Hydrochloric Acid to produce Aqua Regia. This ancient solution is one of the few solutions capable of dissolving both gold and platinum which in turn can be used to purify both metals. The woods 'Aqua Regia' literally translate as 'Royal Water' or 'King's Water' because it was used in ancient times to dissolve the 'royal' or 'noble' metals of gold and platinum.
As well as cleaning and etching glassware, Aqua Regia is also the preferred cleaning medium for NMR tubes as it does not leave any ionic residue, unlike the alternative Chromic Acid which does tend to leave ionic residues.
Because of its strong oxidising nature, Nitric Acid can be used to etch metals and also to dissolve them into solution for analysis by Flame Atomic Absorption Spectrometry and ICPMS (Inductively Coupled Plasma Mass Spectrometry) for analysis in the laboratory.