கொஞ்சம் கெமிஸ்ட்ரி ! - EP.005

 

Chemical Properties

• Formula: HCl

• Molar Mass: 36.46 g/mol

• Appearance: Colorless gas or aqueous solution

• Odor: Pungent, irritating odor

• Density: 1.21 g/L (gas), 1.18 g/cm³ (aqueous solution, 37%)

• Melting Point: -114.2 °C

• Boiling Point: -85.05 °C (gas), varies with concentration for the aqueous solution

• Solubility: Highly soluble in water, forming hydrochloric acid; also soluble in alcohols and other polar solvents

Physical Properties

• State: Gas at standard temperature and pressure (STP), but commonly used as an aqueous solution

• Structure: Diatomic molecule with a single covalent bond between hydrogen and chlorine atoms

Preparation

• Laboratory Method: Direct combination of hydrogen gas (H₂) and chlorine gas (Cl₂) in the presence of UV light or a catalyst:

$${\text{<span style="font-family: Diphylleia;">H</span>}}_{\mathrm{<span\; style="font-family:\; Diphylleia;">2</span>}}<span\; style="font-family:\; Diphylleia;">+</span>{\text{<span style="font-family: Diphylleia;">Cl</span>}}_{\mathrm{<span\; style="font-family:\; Diphylleia;">2</span>}}<span\; style="font-family:\; Diphylleia;">\to </span>\mathrm{<span\; style="font-family:\; Diphylleia;">2</span>}\text{<span style="font-family: Diphylleia;">HCl</span>}\backslash text\{H\}\_2\; +\; \backslash text\{Cl\}\_2\; \backslash rightarrow\; 2\; \backslash text\{HCl\}$$

• Industrial Method: By-product of the chlor-alkali process, where electrolysis of sodium chloride (NaCl) solution produces chlorine gas, which is then reacted with hydrogen gas to form hydrogen chloride.

Uses

• Chemical Industry: Used in the production of various chemicals, such as vinyl chloride (for PVC), fertilizers, and dyes.

• Laboratory Reagent: Used in analytical chemistry and various laboratory processes.

• Pharmaceuticals: Used in the synthesis of active pharmaceutical ingredients (APIs).

• Food Industry: Used as an acidity regulator and to process certain foods.

• Metal Cleaning and Pickling: Employed in removing rust and scale from metals.

• Water Treatment: Used to control pH and as a disinfectant.

Safety and Hazards

• Hazard Statements: H314 (Causes severe skin burns and eye damage), H335 (May cause respiratory irritation)

• Precautionary Statements: P260 (Do not breathe dust/fume/gas/mist/vapors/spray), P280 (Wear protective gloves/protective clothing/eye protection/face protection), P301+P330+P331 (IF SWALLOWED: Rinse mouth. Do NOT induce vomiting), P305+P351+P338 (IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing), P310 (Immediately call a POISON CENTER or doctor/physician)

• NFPA 704 (Fire Diamond): 3 (Health), 0 (Flammability), 1 (Reactivity)

Environmental Impact

• Acid Rain: Hydrogen chloride gas can dissolve in atmospheric moisture, forming hydrochloric acid, which contributes to acid rain and environmental damage.

Handling and Storage

• Handling: Use in well-ventilated areas; avoid inhalation and contact with skin and eyes; use appropriate personal protective equipment (PPE).

• Storage: Store in tightly sealed containers made of corrosion-resistant materials; keep away from incompatible substances such as bases and oxidizers.

Hydrogen chloride is a versatile and widely used chemical compound, but it must be handled with care due to its corrosive nature and potential health hazards.