Hydrochloric acid (HCl) is a clear, colorless, highly pungent solution of hydrogen chloride (HCl) in water. It is a strong acid, meaning that it completely dissociates in water to produce hydrogen ions (H+), and is commonly used as a laboratory reagent and in many industrial processes, such as the production of fertilizers and dyes. Hydrochloric acid is also a component of gastric acid in the digestive systems of most animal species, including humans.
Chemical properties
Hydrochloric acid, HCl, is a strong and highly corrosive mineral acid with the following chemical properties:
- Molecular formula: HCl
- Molecular weight: 36.46 g/mol
- Appearance: colorless to slightly yellowish, fuming liquid
- Boiling point: -85.3 °C
- Melting point: -114.0 °C
- Density: 1.19 g/mL (at 20°C)
- Solubility: Soluble in water and ethanol
- pH: The solution of HCl in water is acidic with a pH of around 1-2
- Reactivity: Reacts with metals and metal oxides to release hydrogen gas, and reacts with most organic compounds and many bases to release chloride ions.
- Storage: HCl should be stored in a cool, well-ventilated area, away from any flammable or reactive materials.
Note: The concentration of HCl solutions is usually expressed as molarity (M) or normality (N). It is important to handle HCl with caution as it can cause severe skin and eye burns and can damage clothing and other materials.
Physical properties
Hydrochloric acid is a clear, colorless, and highly pungent solution with a distinctive smell. It is a strong and highly corrosive acid with a pH of less than 1.0. It is soluble in water and has a high boiling point. The concentration of hydrochloric acid typically ranges from 20% to 37%. The physical properties of hydrochloric acid can be affected by temperature, pressure, and impurities in the solution.
Applications
Hydrochloric acid (HCl) is a versatile chemical with various applications in industries such as:
- Steel Pickling: To remove rust or iron oxide scale from iron or steel before further processing
- Inorganic Compounds Production: Dissolving of metals, metal oxides, and metal carbonates
- pH Control and Neutralization: Regulating the acidity (pH) of solutions in food, pharmaceutical, and drinking water production
- Ion Exchange Regeneration: Regenerating ion exchange resins used in demineralized water production
- Laboratory Use: Acidifying reagent and titrant in chemical analysis
- Other: Leather processing, household cleaning, building construction, and oil well stimulation by dissolving a portion of the rock to create a large-pore structure.
Note: Hydrochloric acid must be handled with care as it is a strong irritant and corrosive to skin, eyes, and respiratory tract.