Nitric acid is a strong acid which is also called aqua fortis or spirit of nitre. This acidic compound is colorless but is an extremely corrosive liquid that can cause burns. It is available in the market in different concentrations and the most popular is the fuming type which contains more than eighty-six percent of the acid. The strength of the acid is due to complete dissociation of ions in water upon dissolution. The acid reacts with alkaline compounds to form nitrates, most of which are highly soluble in water. At high concentrations, it fumes to give reddish or yellowish vapors.
Usually, the synthesis of this acid is possible by letting water and nitrogen dioxide react to develop the pure form of the acid. Another means to obtain the acid is through mixing sulphuric acid and potassium nitrate. Distillation of the products shall yield solid remnants of the precipitate potassium bi-sulphate and the reddish vapor of the acid shall be collected. Reaction and distillation involves glass apparatuses because the acid reacts with cork and rubber to cause leakage that is very hazardous. The acid can also be obtained through the oxidation of ammonia, after which the product is further diluted in water. This technique Acidaburn is important in the production of ammonium nitrate which is used as fertilizer. The white fuming acid is known to be the pure form and is virtually anhydrous, containing very little water. White fuming HNO3 only has two percent water with traces of dissolved nitrogen dioxide. As the amount of nitrogen dioxide increases, the acid fume assumes a reddish color and so it is called red fuming nitric acid. It contains up to seventeen percent of nitrogen dioxide as contrasted to the 0.5% for the white fuming type.
When stored in metal storage tanks, an addition of traces of hydrogen fluoride prevents corrosion of metal tanks as the fluoride ion creates a protective film on the metal surface.
The production of this acid is useful in the manufacture of explosives (nitroglycerin and TNT) and fertilizers (ammonium nitrate) through the reaction of the acid with other substances. Fertilizers derived from this acid are major sources of nitrogen which is an important element for plants. In chemistry labs, the acid is present in various concentrations and is used as a reagent. As a matter of fact, dilute concentrations of the acid is useful in finding out traces of metals in solutions, taking into account that the acid effectively reacts with most metals. Hence, its applications in metallurgy are crucial. Furthermore, this acid can be mixed with hydrochloric acid to form aqua regia which is used to dissolve gold and platinum (known as royal metals).
As mentioned earlier, the acid is a dangerous chemical but is found in nature as acid rain which forms when oxides of nitrogen enter the atmosphere and become incorporated during the condensation of water vapor. Acid rain is an environmental hazard and can destroy forests and render lakes and streams acidic. In laboratories, handling of the chemical should come with caution because it corrodes the skin and destroys its keratin layer causing a yellowish discoloration on the surface.
On the other hand, the chemical is known to be an effective oxidizing agent and reacts with cyanides and metals can be explosive. At the same time, it reacts violently with organic compounds such as turpentine. The explosive, corrosive, and fuming properties of the acid require intense care during usage. People working with it are required to wear protective gear to avoid inhalation of fumes and skin contact with the acid. Laboratories should be well ventilated, too, and wearing of facial masks is also necessary.