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The Nature and Safety Measures of Hydrochloric Acid

Mar. 09, 2021

Hydrochloric Acid is an aqueous solution of hydrogen chloride, which is a strong monobasic inorganic acid and has a wide range of industrial uses. Hydrochloric acid is a colorless and transparent liquid with a strong pungent odor and high corrosiveness. Concentrated hydrochloric acid is extremely volatile. Therefore, the hydrogen chloride gas will volatilize when the container containing the concentrated hydrochloric acid is opened and combine with the water vapor in the air to produce small droplets of hydrochloric acid, causing acid mist to appear above the bottle mouth.

Hydrochloric Acid

Hydrochloric Acid

Physical and chemical properties

Hydrochloric acid is a colorless liquid, an aqueous solution of hydrogen chloride, with a pungent odor. Because concentrated hydrochloric acid is volatile, the volatile hydrogen chloride gas reacts with the water vapor in the air to form small droplets of hydrochloric acid, so white mist will be seen. Hydrochloric acid is arbitrarily miscible with water and ethanol, and hydrogen chloride can be dissolved in many organic solvents. Heat is released when concentrated hydrochloric acid is diluted.

Chemical properties


When the hydrochloric acid is dissolved in the lye, it neutralizes with the lye.


Hydrochloric acid is reductive and can react with some strong oxidants to release chlorine gas


After some metal compounds are dissolved in hydrochloric acid, the metal ions will be complexed with chloride ions.

Copper is difficult to dissolve in dilute hydrochloric acid when there is no air, but it can dissolve in hot concentrated hydrochloric acid and release hydrogen.

Organic chemistry

In acidic environment, nucleophilic substitution of alcohols can generate halogenated hydrocarbons;

Hydrogen chloride can also add olefinic double bonds to obtain chlorinated hydrocarbons;

Amine can be separated from other organic compounds;

Safety measures

Health hazard

Concentrated Hydrochloric Acid (fuming hydrochloric acid) will volatilize acid mist. Both hydrochloric acid itself and acid mist will corrode human tissues and may irreversibly damage respiratory organs, eyes, skin, and gastrointestinal tract. When hydrochloric acid is mixed with oxidants (such as bleaching agent sodium hypochlorite or potassium permanganate, etc.), toxic gas chlorine will be produced.

Hazard prevention

1. Operational matters

When using hydrochloric acid, personal protective equipment should be used. Such as rubber gloves or PVC gloves, goggles, chemical-resistant clothing and shoes, etc., to reduce the risk of direct contact with hydrochloric acid. Airtight operation, pay attention to ventilation. The operation is as mechanized and automated as possible. Operators must undergo special training and strictly abide by the operating procedures.

It is recommended that operators wear self-priming filter gas masks (full face masks), wear rubber acid and alkali resistant clothing, and rubber acid and alkali resistant gloves. Keep away from flammable and combustible materials. Prevent the vapor from leaking into the air in the workplace. Avoid contact with alkalis, amines, and alkali metals. When handling, load and unload with care to prevent damage to packaging and containers. Equipped with leakage emergency treatment equipment. Empty containers may be harmful residues.

2. Acid mist treatment

In the process of using hydrochloric acid, a large amount of hydrogen chloride gas is generated. The suction device can be installed beside the container, and the equipment and facilities such as fan, acid mist purifier, air duct, etc. can be used to discharge the hydrochloric acid mist for outdoor treatment. An acid mist inhibitor can also be added to hydrochloric acid to suppress the volatilization of hydrochloric acid acid mist.

3. Leakage emergency treatment

Emergency treatment: Quickly evacuate personnel from the contaminated area to a safe area, isolate them, and strictly restrict access. It is recommended that emergency personnel wear self-contained positive pressure respirators and wear acid-alkali-proof overalls. Do not directly touch the leakage. Cut off the source of leakage as much as possible.

A small amount of leakage: mix with sand, dry lime or soda ash. It can also be rinsed with a large amount of water, diluted with clean water, and put into the waste water system.

A large number of leaks: construct a dike or dig a pit for storage. Use a pump to transfer to a tanker or a special collector for recycling or transport to a waste disposal site for disposal.

4. Fire-fighting measures

Hazardous characteristics: It can react with some active metal powders and release hydrogen. It can produce highly toxic hydrogen cyanide gas in contact with cyanide. It neutralizes with alkali and emits a lot of heat. It is highly corrosive.

Extinguishing method in the presence of hydrochloric acid: neutralize with alkaline substances such as sodium bicarbonate, sodium carbonate, slaked lime, etc. A lot of water can also be used to fight it out.

The company also provides nitric acid and Sulfuric Acid, please feel free to contact us if necessary