Hydrochloric acid

highly corrosive, strong mineral acid in aqueous solution

Hydrochloric acid is a chemical compound. It is a solution of hydrogen chloride (HCl) gas that is dissolved in water. In the past, people called it muriatic acid. It is widely used in industry, and it is also made by the stomach to help digest food. Hydrochloric acid, like all acids, react with bases to produce salts (chlorides).


Dangerous goods labels

In high concentrations, hydrochloric acid can make acidic mists. Both the mist and the solution hurt human tissue. They are caustic, and can cause chemical burns. These can damage the eyes, the skin, the respiratory system, and other organs of the human body.

When hydrochloric acid is mixed with certain chemicals such as bleach, the toxic gas chlorine is made. When working with hydrochloric acid, certain safety measures should be taken. These include using rubber or PVC gloves, wearing goggles to protect the eyes, as well as special clothing that is resistant to chemicals.

Hydrochloric acid reacts with some metals, corroding them and making flammable hydrogen gas.

The risks of coming in contact with hydrochloric acid depend on its concentration. The following table lists the EU classification of hydrochloric acid solutions:

by weight
Classification R-Phrases
10%–25% Irritant (Xi) R36/37/38
>25% Corrosive (C) R34 R37

The Environmental Protection Agency says hydrochloric acid is a toxin.[1]


  1. "HCl score card". Environmental Protection Agency. Archived from the original on 2009-09-01. Retrieved 2007-09-12.