dissociation

• breaking of a molecule or compound into smaller parts (ions, atoms, radicals, smaller molecules), often reversible
• in water: salts, acids and bases → ions (e.g. NaCl → Na⁺ + Cl⁻), acid strength given by the dissociation constant $K_a$
• thermal dissociation: by heat
• photodissociation (photolysis): by an absorbed photon, e.g. O₂ → 2 O for λ < 242 nm (first step of ozone formation)
• clathrate hydrates: break down into gas and water (or ice) outside their stability field
• dissociation pressure of a clathrate: minimum gas pressure at which it is stable, at a given temperature