Nitric Acid/HNO3,Properties, Synthesis, Reaction and Applications: Complete Amazing Guide

The inorganic mineral acid nitric acid (HNO3) is a highly toxic and harsh liquid that is colorless when pure. It is notorious for its ability to dissolve metals and produce nitrates, as well as for having a strong, suffocating odor. It frequently appears in a variety of scientific applications, business operations, and chemical productions. Nitric acid is frequently used as a reagent in the laboratory for a variety of chemical processes, such as acid-base titrations, redox reactions, and as a part of analytical procedures. It is frequently used to digest materials while creating solutions for elemental analysis.

Physical Properties:

  • Density: nitric acid density is around 1.51 g/cm3
  • Melting point: nitric acid melting point is -42oC
  • Boiling point: its boiling point is 83oC
  • Solubility: It is soluble in water in all proportions
  • Vapor Pressure: 19.9 mmHg at 20°C

Chemical Properties:

  • Acidity: Nitric acid is a potent acid with a low pH that readily dissociates in water to release hydrogen ions (H+).
  • Reaction with Metals: It forms metal nitrates and hydrogen gas (H2) when it interacts with metals like copper and iron.
  • Oxidizing Agent: A range of chemical and inorganic molecules can be oxidized by nitric acid, a potent oxidizing agent. It can produce nitrogen dioxide gas (NO2) and nitrates when it interacts with reducing substances like metals.
  • Reaction with bases:  They produce salts and water as a result. Neutralization is the term for this reaction.

Synthesis or Production:

Ostwald process

Nitrogen dioxide (NO2) is created by the oxidation of ammonia (NH3), and then it is dissolved in water to form nitric acid. There are two main steps in this process: the first is the catalytic oxidation of ammonia, and the second is the nitrogen dioxide absorption in water.

  • Ammonia gas (NH3) is combined with surplus air with the addition of a catalyst such as rhodium gauze or Pt. At temperatures ranging from 800°C to 900°C, the mixture is pushed through a catalytic chamber. Ammonia is converted into nitrogen monoxide (NO) and water vapor when the catalyst is added.

5O2 + 4NH3 → 6H2O + 4NO

  • By reacting with too much oxygen, the nitrogen monoxide (NO) created in the previous stage is further oxidized to nitrogen dioxide (NO2). The gas can be put through more catalytic beds to cause this reaction, or you can use different oxidizing agents.

2 NO + O2 → 2 NO2

  • To create HNO3, nitrogen dioxide gas (NO2) is dissolved in water. The surplus water is normally removed from the resulting nitric acid solution using distillation or another concentration method.

3 NO2 + H2O → 2 HNO3 + NO

Chemical reaction:

  • Dissociation in water

Strong acids, such as nitric acid, totally dissociate in water to produce H+ ions. The solution is acidic because it contains nitrate ions and hydronium ions. The amount of hydronium ions in a solution dictates how acidic it is; more ions mean a more acidic solution. HNO3 contributes a proton (H+) to water (H2O) in this process, creating hydronium ions (H3O+). The dissociation of nitric acid causes the formation of the nitrate ion (NO3-), which occurs simultaneously.

HNO3 + H2O ⇌ H3O+ + NO3-

  • Redox reaction

In redox reactions, nitric acid can also act as an oxidizing agent. Nitric acid, for instance, can be converted to nitrogen oxides in the presence of reducing agents. Nitric acid converts copper into copper (II) nitrate in the reaction, with the formation of water and NO2.

3Cu + 8HNO3 → 3Cu(NO3)2 + 2NO2 + 4H2O

Versatile applications:

It has various applications in different industries and fields. Some common applications of nitric acid include:

  1. Etching and Surface Treatment: Nitric acid is used to etch and treat the surfaces of metals including aluminum, copper, and steel because of its potent acidic characteristics. Metal surfaces are cleaned and prepared for additional processing, such as painting, plating, and coating, using this method.
  2. Applications in the Laboratory and Analytical Setting: It is frequently employed in laboratories as a chemical analysis reagent, particularly when determining the presence of metals and metal ions. It can be used to digest samples, make them acidic, and change pH.
  3. Semiconductor Industry: Silicon wafers are cleaned and etched with nitric acid in the semiconductor industry. During the fabrication process, it aids in clearing impurities and oxide layers off the surface of the wafers.
  4. Chemical manufacturing: It is a common ingredient in the manufacture of several chemicals, including fertilizers, dyes, medicines, and explosives. It is a crucial ingredient in the production of ammonium nitrate, a commonly used explosive and fertilizer.
  5. Production of nitric oxide: Nitric oxide (NO), which is produced from nitric acid, is crucial to the functioning of biological systems. Many biological systems use nitric oxide as a signaling chemical. It is created by body cells and is involved in controlling vascular tone, immunological responses, blood pressure, and neurotransmission.
  6. Explosives and Propellants: The manufacturing of explosives and propellants like nitroglycerin and TNT (trinitrotoluene) depends heavily on nitric acid. It offers these materials the requisite oxidizing characteristics.
  7. Cleaning and Descaling: It is used to clean and descal various systems and equipment, such as boilers, heat exchangers, and pipelines, due to its potent acidic qualities. It aids in removing scale accumulation and mineral deposits.
  8. Metal processing: Nitric acid is used to refine and process metal, particularly in the manufacture of metal alloys such as stainless steel. It has pickling and passivating metals applications to remove impurities and provide corrosion resistance.

Safety considerations:

  • When handling nitric acid, always use the proper protective gear. This comprises protective eyewear, chemical-resistant gloves, a lab coat or other chemical-resistant attire, closed-toe shoes, and safety goggles.
  • To reduce exposure to fumes and vapors, work with nitric acid in a well-ventilated environment or under a fume hood. The buildup of dangerous gases can be avoided with adequate ventilation.
  • Keep nitric acid away from incompatible materials in a cold, dry location with good ventilation. To avoid spills or leaks, it should be kept in an acid-specific cabinet or a secondary containment system.
  • As a potent oxidizing agent, it can react severely with a variety of organic and combustible compounds. Nitric acid must be kept away from flammable substances, potent reductants, and reactive compounds.

Conclusion:

Nitric acid is a versatile chemical reagent that has numerous applications in lab settings and different industries. To guarantee safe and efficient use, it should be handled carefully and in accordance with safety regulations.

How does nitric acid dissociate in water?

Strong acids, such as nitric acid, totally dissociate in water to produce H+ ions. The solution is acidic because it contains nitrate ions and hydronium ions. The amount of hydronium ions in a solution dictates how acidic it is; more ions mean a more acidic solution. Nitric acid (HNO3) contributes a proton (H+) to water (H2O) in this process, creating hydronium ions (H3O+). The dissociation of nitric acid causes the formation of the nitrate ion (NO3-), which occurs simultaneously.
HNO3 + H2O ⇌ H3O+ + NO3-

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