Nitric Acid

Team Chemistry -
Created by: Team Chemistry -, Last Updated: April 27, 2024

Nitric Acid

Nitric acid is a powerful and fascinating substance in the world of chemistry. Known for its sharp, pungent smell and its ability to react with metals. This acid plays a crucial role in various scientific and industrial processes. It’s a liquid that’s not only important for making fertilizers but also in manufacturing explosives and plastics. When you think about acids, nitric acid stands out because of its versatility and the interesting reactions it undergoes.

What is Nitric Acid?

Nitric acid is a strong, corrosive acid that is colorless in its pure form but can appear yellowish over time due to decomposition into oxides of nitrogen and water. Widely used in the manufacturing of fertilizers, explosives, and in the chemical industry, nitric acid plays a crucial role in various chemical reactions. It is known for its sharp, pungent smell and its ability to react with metals, except for gold and platinum. Handling nitric acid requires careful attention due to its reactive nature and the potential for harmful effects if it comes into contact with skin or is inhaled.

Chemical Names and Formulas

NameNitric acid
Alternate NamesAnhydrous nitric acid, Azotic acid, Hydrogen nitrate, Nital, Spirit of nitre

Structure of Nitric Acid


Nitric acid, a key player in both the natural world and industry, has a simple yet fascinating molecular structure. At its core, nitric acid is composed of one nitrogen atom, which acts as the central figure, connected to three oxygen atoms. One of these oxygen atoms forms a double bond with nitrogen, showcasing a strong link, while another oxygen is attached through a single bond but also holds onto an additional hydrogen atom. This unique setup gives nitric acid its acidic properties, allowing it to donate a proton (the hydrogen atom) in chemical reactions. This structure not only explains why nitric acid behaves as a strong acid but also highlights its role in creating nitrates, vital for plant growth and various industrial processes.

Preparation of Nitric Acid

Nitric acid is produced using a method known as the Ostwald process, which involves a few steps and key ingredients: ammonia, oxygen, and water. First, ammonia gas is combined with oxygen gas in the presence of a catalyst, a substance that speeds up the reaction without being consumed by it. This reaction produces nitrogen dioxide (NO2), a reddish-brown gas, and water. The chemical equation for this step is:

4NH₃(g) + 5O₂(g) → 4NO(g) + 6H₂O(g)

In the next step, the nitrogen dioxide reacts with more oxygen and water to finally form nitric acid. This reaction can be represented by the chemical equation

3NO₂(g) + H₂O(l) → 2HNO₃(aq) + NO(g)

Through these reactions, ammonia, a compound that can be produced in large quantities, is transformed into nitric acid, a vital chemical for various industries, including the production of fertilizers and explosives. This process showcases the fascinating transformation of simple molecules into a powerful acid.

Physical Properties of Nitric Acid

AppearanceNitric acid is a colorless liquid, but it can turn yellow or even red-brown upon prolonged exposure to light or heat, due to the decomposition into nitrogen oxides and water.
Chemical FormulaThe chemical formula for nitric acid is HNO₃.
DensityNitric acid has a density of approximately 1.51 g/cm³, making it heavier than water.
Boiling PointIt boils at about83°C (181°F), which is relatively low compared to other acids, indicating its high volatility.
SolubilityIt is highly soluble in water, capable of forming a variety of concentrations, often used in different industrial and chemical processes.
ReactivityNitric acid is highly reactive, particularly with metals, excluding gold and platinum, and forms nitrates, which are integral in many chemical syntheses and applications.

Chemical Properties of Nitric acid

Strong Acidic Nature

  • Nitric acid is a strong acid, meaning it dissociates completely in water to give off hydrogen ions (H+). This property makes it highly effective in acid-base reactions.
  • Equation: HNO₃ → H⁺ + NO₃⁻

Oxidizing Agent

  • One of nitric acid’s most significant properties is its ability to act as a powerful oxidizing agent. It can add oxygen to other substances or remove hydrogen from them. For example, when it reacts with copper, it oxidizes the copper and forms copper nitrate. This reaction also releases nitrogen dioxide, a brown gas, indicating the oxidative nature of nitric acid.
  • Equation: Cu + 4HNO₃ → Cu(NO₃)₂ + 2NO₂ + 2H₂O.

Reactivity with Metals

  • Nitric acid reacts vigorously with most metals, except for gold and platinum, producing nitrates and hydrogen gas or nitrogen oxides depending on its concentration and temperature. For instance, its reaction with magnesium forms magnesium nitrate.
  • Equation: Mg + 2HNO₃ → Mg(NO₃)₂ + H₂


  • When heated, nitric acid can decompose into water, nitrogen dioxide (a toxic and corrosive brown gas), and oxygen​. This property requires careful handling of nitric acid, especially at high temperatures.
  • Equation: 4HNO₃ → 2H₂O + 4NO₂ + O₂

Formation of Nitro Compounds

  • Nitric acid is essential in the manufacture of nitroglycerin and other nitro compounds, which are used in explosives and pharmaceuticals. The acid typically reacts with organic compounds like glycerol to form these substances, a key process in the production of dynamite.

Nitric Acid ( HNO₃) Chemical Compound Information

Chemical Identifiers

CAS registry number7697-37-2
PubChem compound ID944
PubChem substance ID24853516
SMILES identifierN+(O)[O-]
InChI identifierInChI=1/HNO3/c2-1(3)4/h(H,2,3,4)/f/h2H
MDL numberMFCD00011349

NFPA label

NFPA health rating3
NFPA fire rating0
NFPA reactivity rating1
NFPA hazardsOxidizing agent

Uses of Nitric Acid


Fertilizer Production

One of the primary uses of nitric acid is in the production of ammonium nitrate, a compound widely used in fertilizers. This helps plants grow faster by providing them with essential nitrogen.

Manufacturing Explosives

Nitric acid is also crucial in the manufacture of explosives. It reacts with organic compounds to form nitro compounds like nitroglycerin and TNT, which are essential in mining and construction.

Chemical Synthesis

In the chemical industry, nitric acid is used to produce various chemicals, especially those that contain nitrogen. It serves as a starting material for producing plastics, dyes, and pharmaceuticals.

Nitric acid plays a role in the purification and etching of metals. It is used to clean metal surfaces before painting or soldering and can also etch designs into metal for jewelry and electronics.

Making Nitrocellulose

Another interesting application of nitric acid is in the production of nitrocellulose, which is used in lacquers and early photographic films. Nitrocellulose is created by reacting cellulose with nitric acid, resulting in a substance that forms a durable and clear film.

Analytical Reagent

In laboratories, nitric acid is commonly used as a reagent in chemical analyses. It helps identify the presence of certain substances by producing distinctive color changes or reactions.

Side Effects of Nitric Acid

  • Skin Burns: Nitric acid can cause severe burns if it comes into contact with the skin. It reacts quickly upon contact, damaging skin tissue and leading to painful injuries.
  • Respiratory Issues: Inhaling nitric acid fumes can irritate the respiratory tract. Prolonged exposure to these fumes can lead to serious respiratory problems, including pulmonary edema, which is a condition where fluid accumulates in the lungs.
  • Eye Damage: Splashes or vapors of nitric acid can cause significant harm to the eyes. Direct contact with the acid can result in temporary or permanent vision loss due to its corrosive nature.
  • Environmental Harm: When nitric acid is released into the environment, it can cause damage to aquatic life and disrupt ecosystems. It can lead to acidification of water bodies, harming fish and other aquatic organisms.
  • Material Corrosion: Nitric acid can corrode metals and some plastics. This makes it a hazard not only in terms of direct contact but also in terms of structural damage to containers and equipment, which can lead to leaks or failures.


Why is Nitric Acid a Strong Acid?

Nitric acid is a strong acid because it completely dissociates into hydrogen ions and nitrate ions in water, enhancing its reactivity.

What Does Nitric Acid Do to the Body?

Nitric acid can cause severe burns, respiratory distress, and damage to the eyes upon contact or inhalation due to its corrosive nature.

Does Coffee Increase Nitric Oxide?

Yes, coffee can increase nitric oxide levels in the body, improving blood flow and vascular function due to its antioxidant content.

Is Nitric Oxide Bad for Your Kidneys?

In moderation, nitric oxide is beneficial and helps regulate blood flow. However, excessive levels can contribute to kidney damage and disease.

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