The most used acids in the chemical industry are NITRIC ACID (HNO3) and SULFURIC ACID (H2SO4).

1) NITRIC ACID
This strong acid is also highly oxidant; it can be obtained pure, with a
density d = 1.52 g/cc but it's unstable and tends to decompose into NO (nitrogen monoxide); so, in commerce it can be found in water solution at 68% maximum, with d = 1.405 g/cc, as an azeotropic mixture (the particular composition at which H2O and HNO3 distillate together and can't be separated anymore).

PREPARATION
The largest part of this acid is produced with the OSTWALD PROCESS (1908), based on the catalytic oxidation of a gaseous mixture of AMMONIA (NH3, about 10%) and AIR to NO that is further oxidized to NO2 (NITROGEN DIOXIDE) that, in the presence of water vapour, undergoes a disproportion to produce HNO3 and HNO2 (NITROUS ACID).
The nitrous acid gives another disproportion to produce further HNO3 and NO, again oxidized by air and sent back in cycle.
This process is performed at about 750 C, some Atm of pressure and making pass the gaseous mixture at high speed through a metallic network of a Pt/Rh (Platinum/Rhodium) catalyst for not more than 0.0004 sec., to avoid the formation of N2 that would decrease the yield of this process. Here are the reactions:

4NH3 + 5 O2 -> 4NO* + 6H2O
NO + 1/2 O2 -> NO2
2NO2 + H2O -> HNO3 + HNO2
3HNO2 -> H3O+ NO3- + 2NO*

USES
HNO3 is widely used in the production of nitrogen containing fertilizers for agriculture, in the organic synthesis industry as nitrating agent (to introduce the -NO2 group in an organic molecule) to produce nitro-compounds and intermediate products for colorants.
Then, it's employed for PHOSPHORIC ACID (H3PO4) production and in metallurgy, to dissolve metals (except for Pt, Ir, Ti, Ta, Rh, Au).

2) SULFURIC ACID
Very strong and corrosive acid, well known for carbonizing carbohydrates like paper, sugar and wood, given its high dehydrating ability.
The commercial concentrated acid is a colourless and oily solution of H2SO4 (96-98% and water with d = 1.84 g/cc; it's much more stable than concentrated HNO3 and boils at 330C, but it has a minor oxidating properties.

PRODUCTION
The most ancient industrial production system was the LEAD CHAMBERS PROCESS, performed the first time in Great Britain (1746), based on the catalytic oxidationof SO2 to SO3, the last adsorbed in H2O to give the acid.
The catalyst was NO, a gas.
This process has been widely used until the 1950's, when the SO2 frequently

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