Nitrogen: Introduction of Nitric Acid

Nitric Acid is a colourless chemical that is highly corrosive and toxic. It can often turn into a very slight tinge of yellow when stored for longer. This happens due to the high reactivity of nitric acid, as it reacts with the oxygen present inside the container and in the environment when exposed. Nitric acid is usually used in the manufacturing of fertilisers and heavy explosives. Handling nitric acid carefully is extremely important as when it is exposed to bare skin, it can cause severe burns. Let us study nitric acid formula and nitric acid structure to understand more about its nature.

Nitric Acid Sstructure (HNO3)

Nitric acid, a highly oxidising element, comprises three oxygen atoms, one nitrogen atom and a Hydrogen atom. All three oxygen molecules are connected to nitrogen, and one out of those three oxygen molecules is attached to both Nitrogen and Hydrogen. You can see the figure below to get a better idea of the structure.

The nitrogen atom has a positive charge, while the oxygen atom has a negative charge. A positive charge on an atom denotes a lesser electronegative nature, whereas a negative charge means more electronegative. Because nitrogen carries a positive charge, it is less electronegative than oxygen atoms.

Nitric acid is far more abundant around us than we assume. Any bag of fertiliser you purchase contains Nitric Acid in it, and rainwater being acidic, contains trace amounts of nitric acid within itself. 

Preparation of Nitric Acid

As we all read above, there are various natural sources for Nitric Acid, but are those sources enough to meet our requirements? Today the consumption of nitric acid is at an all-time high, and to meet needs, we started producing nitric acid in laboratories. To obtain nitric acid, the chemist heats a nitrate salt in the presence of strong sulphuric acid. The reaction that occurs is-

NaNO3 + H2SO4 → NaHSO4 + HNO3 

On further development of technology, we have now started producing Nitric acid in factories by a method in which an electric arc is created between two water-cooled copper electrodes and the air is blown in between them, ionising the molecules. In contrast, nitric acid is spread into a disc with the help of a right-angle magnetic field. In some cases, Ostwald’s method is implied to produce enormous quantities of nitric acid. This is accomplished through the oxidation of anhydrous ammonia to nitric oxide. At high temperatures, this reaction requires the presence of a platinum catalyst.

Properties of Nitric acid

Natural properties of nitric acid

• Nitric acid has a powerful, acrid and pungent smell and releases heavy vapours

• Nitric acid changes its colour with time, as it is highly reactive with oxygen with the use

• The colour may turn yellowish from a transparent solution

• Nitric acid is available in various concentrations, and all of its different concentrations have multiple colours like red, yellow and others 

• In industries, nitric acid is used at 68% concentration, and for its various other applications, it is used in a concentration of 52-68%

• Nitric Acid fumes at concentrations above 85%, and the red colour in nitric acid that we discussed above comes at a 95% concentration

• The pH of nitric acid is 3.01, the molar mass is 63.01 g/mol, and the density is 1.51g/cm3

• The boiling point of nitric acid is 830C

Chemical Properties of natural acid

• Nitric acid is a highly corrosive, solid and monoprotic acid

• As the name itself suggests, Nitric acid is acidic and turns a blue litmus solution into red

• It decomposes quickly in heat or light to form brown nitrogen dioxide

• Because of this, it turns brownish over time, even though fresh nitric acid is colourless

• Many non-metallic compounds react violently with it

• It also reacts with metals and dissolves metals, producing metal oxide

Conclusion 

Nitric acid today plays a vital role in our day to day life. From getting used in fertilisers to the protection of nylon fibres, nitric acid has a variety of applications. In this article, we studied firstly what nitric acid is? How nitric acid behaves with various other elements, we found out that nitric acid is highly corrosive, being an excellent oxidising agent. We studied the structure of nitric acid and understood the position of atoms in it. We also looked into various production processes of nitric acid and how nitric acid is prepared inside of a laboratory, and how it is prepared commercially. To study more about Ostwald’s approach, you can check our article.