Proton Transfer Equilibrium

Proton Transfer Equilibrium. Presentation Prepared by: Muhammad Farooq EB24209004005 Final Year (Analytical Chemistry) University of Karachi.

Introduction. Acid-base chemistry is important in chemistry and biology Proton transfer occurs between acids and bases Water acts as the main medium for proton transfer These reactions explain pH, buffers, and ionization.

Proton Transfer Equilibrium. Acids donate protons (H⁺) Bases accept protons Reactions are reversible Equilibrium depends on acid strength.

Proton in Aqueous Solution. Free proton cannot exist alone in water Proton combines with water to form H₃O⁺ Hydronium concentration determines acidity Proton movement occurs by proton hopping.

Brønsted-Lowry Theory. Acid = Proton donor Base = Proton acceptor Explains acid-base reactions clearly Useful in aqueous and non-aqueous systems.

Protonation and Deprotonation. Protonation means gaining H⁺ Deprotonation means losing H⁺ Important in proteins and enzymes Affects molecular charge and reactivity.

Conjugate Acid-Base Pairs. Two species differ by one proton Acid forms conjugate base after losing H⁺ Base forms conjugate acid after gaining H⁺ Important in buffer systems.

Acid Dissociation Constant (Ka). Ka measures acid strength Large Ka = Strong acid Small pKa = Strong acid Used in pH and buffer calculations.

Base Dissociation Constant (Kb). Kb measures base strength Large Kb = Strong base Related to Ka by Kw Important in weak base calculations.

Amphiprotic Species. Can donate and accept protons Examples: H₂O, HCO₃⁻ Maintain pH balance Important in biological systems.

Autoprotolysis of Water. Water ionizes into H₃O⁺ and OH⁻ Basis of pH scale Pure water has equal H₃O⁺ and OH⁻ Kw = 1.0 × 10⁻¹⁴ at 25°C.

Buffer Solutions. Buffers resist pH changes Weak acid + conjugate base system Important in blood chemistry Used in pharmaceuticals and industries.

Henderson-Hasselbalch Equation. pH = pKa + log([A⁻]/[HA]) Used to calculate buffer pH Buffer works best when acid and base are equal.

Applications. Blood buffering systems Drug absorption and stability Water treatment and acid rain studies Industrial chemical processes.

Conclusion. Proton transfer equilibrium is a fundamental chemistry concept Explains acid-base reactions and pH behavior Important in chemistry, biology, and industry Helps understand equilibrium systems clearly.

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