Nitric Acid

Properties of Nitric Acid

Nitric Acid displays the properties of a strong acid and it is a powerful oxidising agent.

Reactions of Nitric Acid


Cuprous Oxide, Cu2O reacts with dilute Nitric Acid, HNO3, in the cold to form a solution of Cupric Nitrate, Cu(NO3)2, and Copper, Cu. 
  Cu2O  +  2 HNO3   ==>   Cu(NO3)2   +   Cu   +   H2O
Cuprous Oxide, Cu2O reacts with concentrated Nitric Acid, HNO3, or with dilute Nitric Acid, HNO3, on heating, when the Cuprous Oxide, Cu2O dissolves with evolution of Nitric Oxide, NO. 
  3Cu2O + 14HNO3 ==>   6Cu(NO3)2 + 2NO + 7H2O
Dinitrogen Pentoxide, N2O5, is best prepared by dehydrating concentrated Nitric Acid, HNO3, by Phosphorus Pentoxide, P2O5. 
  2 HNO3   +   P2O5   ==>   N2O5   +   2 HPO3
Nitric Oxide, NO is prepared by the action of Copper, Cu, or Mercury, Hg, on dilute Nitric Acid, HNO3, and was called Nitrous Air. 
               3 Cu   +   8 HNO3    ==>   3 Cu(NO3)2  +  2 NO  +  4 H2O
If reaction Cu with hot HNO3 will produce NO2 gas.
3Cu(s) + 8HNO3(aq) –> 3Cu(NO3)2(aq) + 2NO(g) + 4H2O(l)
Nitrogen Dioxide, NO2, is a mixed acid anhydride and reacts with water to give a mixture of nitrous and nitric acids. 
  2 NO2   +   H2   ==>   HNO2   +   HNO3
If the solution is heated the nitrous acid decomposes to give nitric acid and nitric oxide. 
  3 HNO2   ==>   HNO3   +   2 NO   +   H2O
Sulphur Dioxide, SO2, and Nitrogen Oxides, NOx, are toxic acidic gases, which readily react with the Water, H2O in the atmosphere to form a mixture of Sulphuric Acid, H2SO4, Nitric Acid, HNO3, and Nitrous Acid, HNO2, . The dilute solutions of these acids which result give rain water a far greater acidity than normal, and is known as Acid Rain.
Nitrates are the salts of nitric acid, and are strong oxidising agents.
The Oswald Process is the tree stage process by which Nitric Acid, HNO3, is manufactured. Firstly, Ammonia, NH3, is oxidised, at high temperature (900 deg.C.) over a platinum-rhodium catalyst, to form Nitrogen Monoxide, NO. 
  4 NH3 (g)   +   5O2 (g)   ==>   4 NO (g)   +   6H2O
The Nitrogen Monoxide, NO, cools and reacts with oxygen, O2, to produce Nitrogen Dioxide, NO2. 
   2 NO (g)   +   O2   ==>   2 NO2 (g)
Finally, the Nitrogen Dioxide, NO2 reacts with Water, , and Oxygen, O2, oxygen to produce Nitric Acid, . 
  4 NO2 (g)   +   2 H2O (l)   + O2   ==>   4 HNO3 (l)
Boron, B, is oxidised by Nitric Acid, HNO3, to Boric Acid, H3BO3.
Detection and Analysis
Boron, B, is detected by converting the material under analysis to Borax, Na2B4O7.10H2O, by heating with concentrated Nitric Acid, HNO3, and then heating with concentrated Sulphuric Acid, H2SO4, and Ethanol, C2H5OH, to form Ethyl Borate, C2H5H2BO3, which burns with a green flame. Copper, Cu, is below Hydrogen, H2, in the electrochemical series and thus, does not react with acids to liberate Hydrogen, H2, unless they are also strong oxidising agents. Thus, Copper metal, Cu, will not react with dilute Sulphuric Acid, H2SO4, or with Hydrochloride Acid, HCl, but it reacts with Nitric Acid, HNO3, to form Oxides of Nitrogen, NOx. Cuprous Oxide, Cu2O reacts with dilute Nitric Acid, HNO3, in the cold to form a solution of Cupric Nitrate, Cu(NO3)2, and Copper, Cu. 
            Cu2O  +  2 HNO3   ==>   Cu(NO3)2   +   Cu   +   H2O
Cuprous Oxide, Cu2O reacts with concentrated Nitric Acid, HNO3, or with dilute Nitric Acid, HNO3, on heating, when the Cuprous Oxide, Cu2O dissolves with evolution of Nitric Oxide, NO. 
  3 Cu2O   +   14 HNO3        ==>   6 Cu(NO3)2   +   2 NO   +   7 H2O
When glycerol is injected carefully, in the form of a spray, into a well-cooled mixture of concentrated Nitric Acid, HNO3, and Sulphuric Acid, H2SO4, Glyceryl Trinitrate, (i.e. the nitric acid ester of glycerol), is obtained. This nitrated compound is wrongly called nitro-glycerin. 
  CH2OH    CH2ONO2   CHOH  +  3HONO2 ==>         CHONO2   CH2OH    CH2ONO2 
 Glyceryl Trinitrate      (Nitro-glycerin)

Comments

Post a Comment