Hydrochloric acid is a strong inorganic acid widely used in chemical production, metallurgy, and pharmaceuticals. It plays a crucial role in regulating pH levels, removing impurities, and disinfecting water.
Additionally, it is naturally present in the human stomach. The concentration of hydrochloric acid in gastric juice is 0.5%, which is sufficient to digest proteins.
Properties of hydrochloric acid
Hydrochloric acid is a clear liquid that appears colorless in its pure form. However, it can turn yellow or yellow-green when it contains impurities of silver or iron ions. It has a sharp, irritating odor and is highly corrosive.
Hydrochloric acid is highly soluble in water and has pronounced corrosive properties against most metals and their oxides.
Hydrochloric acid is classified as a level-three hazardous substance. This reagent is non-flammable and non-explosive. In its concentrated form, it is highly volatile and tends to “smoke” when exposed to open air. This is because it reacts chemically and releases hydrogen chloride.
The concentration of hydrogen chloride used in different industries can vary. Although the standard concentration of hydrogen chloride is 38%, it may increase up to 40% depending on the industry. The concentration of hydrogen chloride has an impact on the measures that need to be taken during transportation, storage, and interaction with hydrochloric acid. The higher the concentration, the more safety measures are required.
Briefly about the synthesis of hydrochloric acid
Jabir ibn Hayyan, the famous Arab alchemist, discovered hydrochloric acid in 800 AD through a mixture of salt and vitriol. Centuries later, in the 15th century, V. Valentine synthesized hydrogen chloride through the heating of iron (II) sulfate and salt, resulting in hydrochloric acid. That reagent was also known as the “spirit of salt”.
Over time, the German alchemist I. Glauber managed to extract hydrochloric acid by combining salt and sulfuric acid. Its chemical composition was then discovered in 1790 by the British chemist G. Davy, who synthesized the substance using hydrogen and chlorine.
During the industrial synthesis of sodium carbonate, hydrogen chloride was released as a byproduct of a chemical reaction. Initially, it was released into the air, but in 1863, the English Parliament passed a law that required chemical industry enterprises to dispose of the reagent in water. This marked the beginning of industrial-scale production of hydrochloric acid.
Currently, synthetic hydrochloric acid (36% and more) is produced by direct synthesis followed by absorption with water.
Absorbent hydrochloric acid with a concentration of 31-33% is produced by absorbing hydrogen chloride released as a by-product during chlorination reactions. The reagent obtained in this way contains various impurities.
Hydrochloric acid in modern industry
Inhibited hydrochloric acid is a commonly used reagent in various industries due to its versatility and effectiveness. Hydrochloric acid is indispensable:
- in the chemical industry, these compounds serve as raw materials for the production of chlorides and derivatives of chlorine;
- in the production of household and industrial chemicals;
- as a coagulant, it is applied to purify drinking water and wastewater for industrial and domestic purposes;
- as a pH level corrector for swimming pool water;
- to soften water in breweries;
- as an acidity regulator, E507 is used in various food products such as syrups, cheeses, curds, infant formula, gelatin, and confectionery;
- in pharmaceuticals during the synthesis of active substances;
- in the construction industry as an ingredient in adhesive mixtures;
- in the metallurgical industry for pickling metals;
- in the leather industry for deliming, tanning, and dyeing leather;
- in the mining industry as a reagent for processing metal ores;
- for the production of pigments and dyes, including cosmetics.
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