2HNO3

2HNO3 refers to two molecules of nitric acid. Nitric acid is a highly corrosive and strong mineral acid with the chemical formula HNO3. In its pure form, it is a colorless liquid, but older samples may develop a yellowish hue due to the decomposition of nitrogen dioxide. Nitric acid is a powerful oxidizing agent and is used in the production of fertilizers, explosives, and propellants. It also plays a role in various industrial chemical processes and laboratory reagents.

Nitric acid is formed industrially by the Ostwald process, which involves the catalytic oxidation of ammonia. This process converts ammonia into nitric oxide, which is then further oxidized to nitrogen dioxide, and finally reacted with water to form nitric acid. The chemical reaction is represented as 4NH3 + 5O2 -> 4NO + 6H2O, followed by 2NO + O2 -> 2NO2, and then 3NO2 + H2O -> 2HNO3 + NO. The NO produced in the last step is recycled back into the process.

In aqueous solution, nitric acid dissociates into a hydronium ion (H3O+) and a nitrate ion (NO3-). Its strong acidic nature means it readily donates a proton. It reacts vigorously with many organic compounds and metals, often producing toxic fumes. Due to its corrosive properties and oxidizing capabilities, nitric acid must be handled with extreme care, using appropriate safety equipment and in well-ventilated areas. The presence of two HNO3 molecules simply indicates a quantity of two individual nitric acid units in a given context, such as in a chemical equation representing a reaction where two moles of nitric acid are consumed or produced.