Answer to Question #308163 in General Chemistry for Sofia

Question

Using chemical equations, show how the triprotic acid H3PO4 ionizes in water. Phases are optional.

𝐾a1:

𝐾a2:

𝐾a3:

Answer 1

• H₃PO₄ = H⁺ + H₂PO₄^-, K_a1;

K_a1 = [H⁺] * [H₂PO₄^-] / [H₃PO₄];

• H₂PO₄^- = H⁺ + HPO₄^2-, K_a2;

K_a2 = [H⁺] * [HPO₄^2-] / [H₂PO₄^-];

• HPO₄^2- = H⁺ + PO₄^3-, K_a3;

K_a3 = [H⁺] * [PO₄^3-] / [HPO₄^2-].

Answer:

Ka1 = [H⁺] * [H₂PO₄^-] / [H₃PO₄];

Ka2 = [H⁺] * [HPO₄^2-] / [H₂PO₄^-];

Ka3 = [H⁺] * [PO₄^3-] / [HPO₄^2-].