By Kevin Beck
Updated Aug 30, 2022

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While "muriatic" is an uncommon term outside of chemistry circles, it refers to the same powerful acid most people recognize as hydrochloric acid (HCl). In everyday language and in most commercial settings, the more familiar name—hydrochloric acid—has largely replaced the historical term.

Hydrochloric acid is a strong, colorless, odorless liquid with the chemical formula HCl. Its acidity is nearly complete, meaning it dissociates almost entirely in water to produce hydronium (H₃O⁺) and chloride (Cl⁻) ions. This property makes it indispensable in laboratories, industry, and even household cleaning.

What Are Acids and Bases?

In aqueous solution, an acid donates a proton (H⁺) to water, forming hydronium ions. The species that remains after proton donation is the acid’s conjugate base. For HCl, the conjugate base is the chloride ion (Cl⁻), derived from the element chlorine.

The dissociation reaction is:
HCl(g) + H₂O(l) → H₃O⁺(aq) + Cl⁻(aq)
Because hydrochloric acid is strong, this reaction proceeds nearly to completion under typical conditions.

History and Discovery

Hydrochloric acid was first produced by the Persian alchemist Jabir ibn Hayyan around 800 CE. Though alchemy is now considered a pseudoscience, early practitioners worked with real substances and laid groundwork for modern chemistry.

The name "muriatic" derives from the Latin *muriaticus*, meaning "briny"—a reference to its production from saltwater solutions.

Key Properties

• Corrosive and toxic—protective eyewear and gloves are mandatory regardless of concentration.
• Noncombustible—HCl does not burn, but it reacts violently with bases and many metals.
• Molecular weight: 36.46 g mol⁻¹, with 95 % of the mass from chlorine.

Industrial Production

HCl can be manufactured by several scalable routes:

• Combustion of hydrogen and chlorine gases:
  H₂ + Cl₂ → 2HCl
• Reaction of sodium chloride with sulfuric acid:
  2NaCl + H₂SO₄ → 2HCl + Na₂SO₄
• Advanced processes using sodium chloride, sulfur dioxide, air, and water vapor:
  4NaCl + 2SO₂ + 2H₂O + O₂ → 2Na₂SO₄ + 4HCl

Applications of Muriatic (Hydrochloric) Acid

• Steel & metal finishing—acid pickling removes oxides before galvanizing or tinning.
• Pharmaceutical synthesis—serves as a catalyst, pH regulator, and reactant in drug production.
• Food industry—used in the manufacture of high‑fructose corn syrup and vitamin supplements.
• Water treatment—adjusts pH of pool, spa, and wastewater to protect aquatic life.
• Petroleum & natural gas—acidifies wells and fracturing fluids to dissolve carbonate minerals, enhancing flow.

Typical Chemical Reactions

HCl reacts with many metals to produce metal chlorides and liberate hydrogen gas. For example:

Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g)