Hydrogen Chloride Gas & Hydrochloric Acid

Introduction to Hydrogen Chloride (HCl)

Hydrogen chloride is a diatomic molecule, consisting of one hydrogen atom and one chlorine atom. It is a colorless gas with a pungent odor and is highly soluble in water, forming hydrochloric acid.

Properties of Hydrogen Chloride Gas

• Physical State: Colorless gas at room temperature.
• Odor: Pungent and irritating smell.
• Solubility: Highly soluble in water.
• Density: Heavier than air.
• Acidity: Forms hydrochloric acid when dissolved in water.

Test for Hydrogen Chloride Gas

• Ammonia Test: When a glass rod dipped in concentrated ammonia solution is brought near HCl gas, dense white fumes of ammonium chloride are formed.

Hydrochloric Acid (HCl)

Hydrochloric acid is a strong acid formed when hydrogen chloride gas dissolves in water. It is commonly used in laboratories and industries.

Properties of Hydrochloric Acid

• Strong Acid: Completely ionizes in water to form hydronium ions $\text{H}_3\text{O}^+$ and chloride ions $\text{Cl}^-$.
• Corrosive: Can cause burns on skin and damage materials.
• Reactivity: Reacts with metals to produce hydrogen gas.

Uses of Hydrochloric Acid

• Industrial Use: Used in the production of chlorides, fertilizers, and dyes.
• Laboratory Use: Commonly used as a reagent in chemical reactions.
• Cleaning Agent: Used to remove rust and scale from metals.

Hydrides and Acid Strength

Hydrogen halides, such as HCl, are hydrides of halogens. The acid strength of hydrogen halides increases down the group in the periodic table.

• Acid Strength Order: HF < HCl < HBr < HI