Hydrochloric acid

Hydrochloric acid (CAS 7647-01-0), also known as HCl and listed as E507 in food applications, is a strong inorganic acid in aqueous solution.

Where is Hydrochloric acid used?

• Industrial-scale pH control, metal processing, and chemical synthesis
• Steel and metal fabrication: pickling and descaling surfaces before galvanizing, electroplating, or coating, removing iron oxides without damaging the base metal
• Food and beverage: E507-grade acid regulates pH in starch hydrolysis and gelatin production and in the manufacture of food additives
• Water treatment: dosing to correct alkalinity and maintain optimal pH in potable water systems and industrial effluent streams
• Leather tanneries and textile processors apply it in deliming, dyeing preparation, and fiber treatment stages.
• Preparation of chlorides and metal salts.
• Production of iron chloride and aluminum chloride.
• Manufacture of vinyl chloride for PVC.
• Oil well acidizing to dissolve calcium and magnesium carbonate rock formations, increasing permeability and production.

Good to know: Its aggressive reactivity with oxides, carbonates, and alkaline compounds makes it a primary reagent. Food and pharma applications require compliance to BP or Ph. Eur. standards to ensure safety and purity.

Formulation notes

• Mixing with bleach produces toxic chlorine gas.
• HDPE is the standard tank and drum material for up to 37% concentration, with a maximum service temperature of 60 °C.
• EPDM and Viton (FKM) elastomers are rated good for service up to 80 °C, while Buna-N (NBR) hardens and cracks.
• Carbon steel and 316 stainless steel are not recommended due to severe pitting and catastrophic corrosion.

Typical specification

• 31% grade has a mass fraction of 30–32%.
• Available in Technical and ACS Reagent grades at 37%.
• Offered in 5%, 10%, 15%, 20%, 25%, 31% and 37% concentrations.
• Industrial grades typically have concentrations of about 32 ± 2% (10 M).

Regulatory status

• Hydrogen chloride has CAS 7647-01-0, EC 231-595-7 and index number 017-002-00-2.
• Aqueous solutions have CAS 7647-01-0, EC 231-595-7 and index number 017-002-01-X.

Storage, packaging and handling

• Packaged in 1200 kg IBC tanks.
• Must be stored in tightly closed containers.

Frequently asked questions about Hydrochloric acid

What safety measures are required when handling hydrochloric acid?

Personal protective equipment (clothing, face and mouth protection) must be used when opening and using the container.

Technical content is compiled and updated by the SoleChem product team from public technical sources; the certificate of analysis (COA) governs product-specific specifications.