Nitric Acid 68%
Nitric acid 68% is light clear-yellow colour liquid, highly corrosive mineral acid. The pure Nitric Acid is colorless, but due to decomposition into oxides of nitrogen and water it becomes yellow over the time.
It is excellent oxidising/reducing agent. Both these properties are exploited in variety of different industries; It should be handled very carefully.
Concentrated Nitric Acid is widely used in making of Aqua regia, mixture of concentrated nitric and hydrochloric acids, usually one part of the former to three parts of the latter by volume. This mixture was given its name (literally, “royal water”) by the alchemists because of its ability to dissolve gold and other so-called noble metals.
Most commercially available nitric acid has a concentration of 68% in water. It is known as fuming nitric acid, at concentration of 86% HNO3. The fuming nitric acid is further characterized as red fuming nitric acid at concentrations above 86%, or white fuming nitric acid at concentrations above 95%.
Applications
Nitric Acid is in integral part of Aqua Regia solution; used in gold refining, recovery and extraction process.
Nitric Acid mixed with Phosphoric Acid makes a solution which is commercially used to remove Efflorescence ( Deposit of salts) from Pavers, Sandstone, slate or Terracotta. This solution is also commonly used for cleaning food and dairy equipment primarily to remove precipitated calcium and magnesium compounds.
Due to high corrosive nature it is used as pickling agent for metals- to remove any rust, scale, inorganic impurities from ferrous metals as well as copper and aluminium alloys.
Nitric acid is mainly used for the production of fertilizers. Nitric acid is neutralized with ammonia to produce ammonium nitrate. This application consumes 75–80% of Nitric Acid produced every year.
At low concentration of ~10% Nitric acid is often used to artificially age pine and maple. It produces grey-gold colour which is very much like very old wax- or oil-finished wood.
Nitric Acid is widely is used in electroplating industry to strip nickel and chrome.
