Uses of Hydrochloric Acid: Common and Industrial Applications

Hydrochloric acid is a strong acid, also known as muriatic acid. It is a colorless solution of hydrogen and chlorine with a pungent smell. It has the chemical formula of HCl. In this compound, hydrogen and chlorine atoms are bonded to each other by a polar covalent bond as the difference in their respective electronegativities is much greater.

There are a large number of applications of hydrochloric acid. It can be used in the synthesis of organic and inorganic substances, preparation of oils and steroids, purification of salts, and pH control of the solutions. It is also used for many domestic purposes in our daily life.

Hydrochloric acid is used in industries to produce fertilizers, dyes, and chlorides. It is also used in electroplating, photographic extraction, rubber, and textile industries.

10 Common Uses of Hydrochloric acid (HCl)

  1. Laboratory reagent
  2. Cleaning agent
  3. Purification of sugars and salts
  4. Resin regenerator
  5. Controlling the pH of the solution
  6. Production of organic and inorganic compounds
  7. Pickling of iron and steel
  8. Polymerization
  9. Synthesis of food additives and oils
  10. Catalytic activities

Laboratory reagent

The major use of muriatic acid (HCl) is as a lab reagent. It is used for the initiation of different chemical reactions. It is also used for acid-base titrations, and the (exact) determination of base as a secondary standard solution.

Cleaning agent

HCl can be used as a cleaning agent due to its corrosive properties. It is used to remove stains and rust from the surface of substances, such as metals, tiles, marble (calcium carbonate), etc.

Purification of sugars and salts

Purification of sugar can be achieved by using hydrochloric acid. For example, sugarcane juice can be purified by reacting with HCl. Hydrochloric acid reacts with the impurities (organic compounds) that can be removed from the rest of the sugarcane juice. In this way, pure and concentrated sugarcane juice can be obtained for sucrose synthesis.

Hydrochloric acid is used for the analysis and purification of salts. For example, sodium chloride table salt (NaCl) can be purified by using hydrochloric acid. The impure form of salt is dissolved in an aqueous solution of hydrochloric acid. The reaction of this acid with metals forms chloride salts.

Resin regenerator

HCl is used for the regeneration of resins, for example, ion exchange resin. To remove the minerals from the water, such as calcium and sodium ions, cation exchangers are used. These cations can later be rinsed from resins by using hydrochloric acid. This results replacement of calcium and sodium ions with hydrogen ions, which is termed as regeneration of resins.

Controlling the pH of the solution

The acidity of the solution can be regulated by changing the pH of the solution. In factories, food can be stored for a long time by maintaining the pH. This can be controlled by using hydrochloric acid.

Production of organic and inorganic compounds

Hydrochloric acid is used for the synthesis of organic and inorganic compounds in laboratories and industries.

Organic compounds, such as vinyl chloride and dichloromethane can be prepared by using hydrochloric acid. These products are then used to produce plastic, e.g. polyvinyl chloride (PVC).

Hydrochloric acid is used for the production of inorganic compounds like chlorides i.e. iron chloride, polymers of aluminum chloride, mustard gas, ammonium chloride, etc.

Pickling of iron and steel

Pickling is the removal of impurities (rust, scale, and oxide layers) that are deposited on the surface of metals such as iron and steel. Impurities are removed from the surface of the metal or alloys by dipping them into the solution of dilute hydrochloric acid. This solution of HCl is known as pickle liquor.

Polymerization

Hydrochloric acid is used as a catalyst for the acid-catalyzed polymerization of monomers. For example, polyethylene is synthesized by the reaction of ethene with HCl and Zieglar-Natta catalyst.

Synthesis of food additives and oils

Muriatic acid is involved in several reactions that are used to synthesize food and its additives. For example, the production of fructose, aspartame, citric acid, lysine, gelatin, etc.

Due to the corrosive nature of hydrochloric acid, it is used for enhancing oil production by adding an oil well to shape the rocks. It dissolves the rocks from the surface and converts them into structures of rocks containing spores. This is known as the oil well acidizing process.

Catalytic activities

The significant uses of hydrochloric acid are as a catalyst in the reactions. It is a key component to speed up the chemical reactions by lowering the activation energy of the reaction systems.

HCl in Human stomach

The human stomach is made up of different types of cells. Parietal cells are responsible for producing the dilute amount of hydrochloric acid in the stomach. The hydrochloric acid and other digestive juices of the stomach are collectively called gastric juice which is responsible for food digestion and maintaining a pH of 1-2 in the human stomach.

The role of hydrochloric acid in the stomach is to activate the pepsinogen (conversion into a more strong form called pepsin that helps further digestion) by lowering the pH of the stomach. When the chyme (mixture of food components in the stomach) enters the duodenum (first part of the small intestine), hydrochloric acid is neutralized by a reaction with bicarbonates from bile juices in the small intestine.

Hydrochloric acid does not affect the stomach because there is a layer, the mucus layer, which protects the animal stomach from acid burns.

Key Uses of HCl in our Daily life

The following are the uses of HCl in our daily lives:

  • HCl is used for kitchen or floor cleaning purposes.
  • It is used for the purification of sugar from sugarcane juice.
  • Dilute hydrochloric acid is used in the chemical laboratories of schools and colleges.
  • HCl is used in the production of glue and gelatin on a small scale.
  • It is secreted and used by the stomach in the human body for digestion.
  • It is used for the analysis of salts in chemical labs.
  • It is used in the synthesis of food additives.

Concepts Berg

Is hydrochloric acid dangerous?

Dilute hydrochloric acid is not dangerous but pure or concentrated hydrochloric acid is very dangerous and corrosive for human skin and eyes. It can easily burn animal skin.

Is hydrochloric acid a compound?

HCl is a colorless compound of hydrogen and chlorine.

Is HCl a volatile acid?

HCl is a gas. It is dissolved in water to make a liquid acid. Therefore there is no question about whether it is a gas or not.

What are some household uses for hydrochloric acid?

At home, we can use dilute hydrochloric acid for cleaning the kitchen floors. It is also used for cleaning bathrooms.

Can we drink HCl?

The human mouth has a pH of 5.4, and HCl is at a pH of 1.0, therefore, it is very much damaging to the mouth tissues. However, it is already present in our stomach as a natural secretion and it does no harm there because of the mucous layer.

What are the reactants of hydrochloric acid?

Hydrogen and chlorine gases are the reactants of hydrochloric acid.

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