Phosphoric acid ionizes in three steps with theirionization constant values 1 2 K ,K a a and 3 Ka ,respectively, while K is the overall ionizationconstant. Which of the following statements aretrue

Answer

Phosphoric Acid Dissociation and Acid Strength

Stepwise Ionization of H₃PO₄:

H₃PO₄ ⇌ H₂PO₄⁻  (K_a1)

H₂PO₄⁻ ⇌ HPO₄²⁻ + H⁺  (K_a2)

HPO₄²⁻ ⇌ PO₄³⁻ + H⁺  (K_a3)

Overall Equilibrium Constant:

K = K_a1 × K_a2 × K_a3

log K = log K_a1 + log K_a2 + log K_a3

Acid Strength Comparison:

(B) Yes, H₃PO₄ is a stronger acid than both H₂PO₄⁻ and HPO₄²⁻, as acidic strength decreases with successive loss of hydrogen. H₃PO₄ has three hydrogen ions available for donation.

Ka Value Relationship:

(C) In H₃PO₄, K_a1 > K_a2 > K_a3 because it becomes increasingly difficult to remove a proton from a negatively charged ion.

Conclusion: Statements A, B, and C are all correct.