Nitric acid or salt essence is one of the most widely used substances in the industry, which is widely used for washing. In the upcoming article, the introduction of this material, its properties, uses, and safety aspects of working with it are discussed.

Nitric acid has other names such as nitric acid, salt essence, nitric acid, hydrogen nitrate, azotic acid and azotic acid. Its chemical formula is HNO3. It is a yellow or colorless substance. Nitric acid has a nasty and pungent smell. Its melting point is -41 °C and its boiling point is 122 °C. This substance is completely soluble in water and is non-flammable. The powder sample of this material usually has two types of single water and three water. The molar mass of this substance is 63 g/mol.

Nitric acid is a highly oxidizing substance and the history of its use goes back to gold mining. Because this acid has the ability to dissolve all metals except gold. This acid is also used to recycle metal waste or computer waste.

Nitric acid may decompose when exposed to light or heat. This is why this acid is usually kept in dark containers. This acid produces NO2 gas when decomposed. This gas is red in color and that is why the vapor of this acid is usually seen in reddish brown color. This is because it is actually nitrogen dioxide that can be seen with this color. This color is seen as a result of the decomposition of nitric acid into water, nitrogen dioxide and oxygen.

In some cases, nitric acid is also used in gaseous form, which usually has lower amounts of NO2.

Chemical formula of nitric acid

Nitric acid is made with the chemical formula HNO3. This material is also known as Dandruff essence. The chemical structure of this substance can be seen in the picture below.

Applications of nitric acid

This acid is used in the production of ammonium nitrate. Ammonium nitrate is one of the types of fertilizers that you can read about in the article “Types of Chemical Fertilizers” . In the following, some uses of nitric acid in various industries are mentioned.

Application of nitric acid in agriculture

Nitric acid is used for digestion and preparation of plant samples. In this process, nitric acid removes the organic parts of the plant. As a result, it allows researchers to measure the elements in the plant. Apart from being used in soil and botanical laboratories, it can also be used to make fertilizer due to its high nitrogen content. But its main use is in the digestive process.

Application of nitric acid in gold extraction

Nitric acid is a very strong acid that has the ability to dissolve many metals. This is the reason why this acid is used along with hydrochloric acid to make Soltani acid. Acid is used to extract gold from old electronic boards by dissolving the metals in electronic boards.

Application of nitric acid in industry

Nitric acid has been used in gold extraction. Nitric acid is also widely used in electronic waste recycling and is one of the main materials.

Nitric acid is also used as an oxidizer in rocket fuel.

One of the main and basic uses of nitric acid is for washing. This acid is a good option for washing due to its corrosiveness and the fact that it can dissolve a large number of metals well.

Nitric acid is often used for chemical analysis. For example, this acid is used to prepare samples for ICP-MS and ICP-AES analyses.

Nitric acid is used to produce explosives, paint, medicine and as a reagent in many processes.

Application of nitric acid in food industry

Nitric acid is used in the production of potassium nitrate. Potassium nitrate is a food additive and coloring agent. This substance is used as a preservative to preserve meats and salty products. (such as sausages)

Nitric acid production method

The best method for the production of nitric acid, which can be done at a low cost and can be used industrially, is to use ammonia as a precursor. In this process, ammonia is prepared under the catalytic oxidation reaction. This reaction is carried out at a temperature of about 150 to 170 degrees Celsius. In this method, the nitric acid produced has a concentration of about 95%. In this method, nitric acid is produced through the following reactions:

4 NH ₃ (g) + 5 O ₂ (g) → 4 NO (g) + 6 H ₂ O (g)

2 NO (g) + O ₂ (g) → 2 NO ₂ (g)

3 NO ₂ (g) + H ₂ O (l) → 2 HNO ₃

4 NO ₂ (g) + O ₂ (g) + 2 H ₂ O (l) → 4 HNO ₃ (aq)

The explanation of the above process is that ammonia gas is oxidized first and leads to the production of nitric oxide and nitrogen dioxide. Next, all nitric oxide is converted into nitrogen dioxide and nitrogen dioxide is absorbed by water, which leads to the formation of nitric acid.

Properties and characteristics of nitric acid

Industrial samples of this material are usually available as a combination with water at a concentration of 68%. If this solution is pure, it is colorless. (Usually the presence of some impurity inside it leads to a partial color change of the solution, which is usually yellow)

As mentioned, this acid is experienced by heat or light. Its decomposition reaction is as follows:

4 HNO ₃ → 2 H ₂ O + 4 NO ₂ + O ₂

This reaction will cause gas production and changes in the pressure around the liquid. Nitrogen oxide produced as a result of decomposition remains in solution and causes its color to turn yellow or red. Pure nitric acid produces a white foam when exposed to air, while if nitrogen oxide is dissolved in it, it produces a reddish-brown foam.

Nitric acid hazards and safety issues

Concentrated nitric acid is a strong oxidizer and in combination with combustible materials, all kinds of alcohols or reducing agents and combustible compounds will produce heat or burn and explode.

This material is very corrosive and precautions should be taken while working with it. If its temperature rises too much, corrosive and toxic gases are released from the material.

This substance is very dangerous if it enters the respiratory tract or eyes.

In the video below (in English), nitric acid vapors can be seen and some safety explanations related to working with nitric acid are given.