Answer
(a) Dissolution of Hydrogen Chloride (HCl) in Water
Hydrogen chloride is a gaseous covalent compound under standard conditions. When it dissolves in water, it undergoes a dissociation reaction, where it donates a proton (H⁺) to water molecules.
Key Concepts:
- HCl (g) is a gas at room temperature (TSS conditions).
- In water, HCl behaves as a strong acid, meaning it completely dissociates into ions.
- The proton (H⁺) from HCl attaches to a water molecule to form hydronium ion (H₃O⁺).
Balanced Chemical Equation:
HCl(g) + H₂O(l) → H₃O⁺(aq) + Cl⁻(aq)
Note: The equation can also be written in a simplified ionic form as:
but the form involving H₃O⁺ is more accurate at the molecular level.
HCl(aq) → H⁺(aq) + Cl⁻(aq), but the form involving H₃O⁺ is more accurate at the molecular level.
Explanation of States of Matter:
- HCl(g): Gaseous hydrogen chloride under TSS.
- H₂O(l): Liquid water, the solvent.
- H₃O⁺(aq): Hydronium ion, aqueous form of proton.
- Cl⁻(aq): Chloride ion dissolved in water.