What Is Muriatic Acid? Facts and Uses

HCl molecule accompanied by a definition of muriatic acid: Muriatic acid (or hydrochloric acid) dissociates in water to form a hydrogen cation (H+) and chloride anion (Cl-).

ThoughtCo / Nusha Ashjaee

Muriatic acid is one of the names for hydrochloric acid, a corrosive strong acid. It is also known as spirits of salt or acidum salis. "Muriatic" means "pertaining to brine or salt". The chemical formula for muriatic acid is HCl. The acid is widely available at home supply stores.

Uses of Muriatic Acid

Muriatic acid has many commercial and home uses, including the following:

  • Industrial synthesis of vinyl chloride and polyvinyl chloride (PVC)
  • Food additive
  • Gelatin production
  • Descaling
  • Leather processing
  • Household cleaning (when diluted)
  • Pickling of steel
  • Production of inorganic chemical compounds
  • pH control of water, food, and drugs
  • Regenerating ion exchange resins
  • Purification of table salt
  • Building construction
  • To dissolve rock in oil production
  • Occurs naturally in gastric acid to digest food

A Note About Concentration

Muriatic acid isn't pure hydrochloric acid, nor is there a standard concentration. It's important to check the product label to know the concentration. Some industrial suppliers offer muriatic acid that is 31.5 percent HCl by mass (20 Baumé). However, other common dilutions include 29 percent and 14.5 percent. 

Muriatic Acid Production

Muriatic acid is prepared from hydrogen chloride. Hydrogen chloride from any of a number of processes is dissolved in water to yield hydrochloric or muriatic acid.

Muriatic Acid Safety

It's important to read and follow safety advice given on the acid container because the chemical is highly corrosive and also reactive. Protective gloves (e.g. latex), eye goggles, shoes, and chemical-resistant clothing should be worn. The acid should be used under a fume hood or else in a well-ventilated area. Direct contact can cause chemical burns and damage surfaces. Exposure can damage the eyes, skin, and respiratory organs irreversibly. Reaction with oxidizers, such as chlorine bleach (NaClO) or potassium permanganate (KMnO4) will produce toxic chlorine gas. The acid can be neutralized with a base, such as sodium bicarbonate, and then rinsed away using a copious volume of water.