Question

What is Ką for H3PO4(aq) = H(aq) + H₂PO4 (aq)?

Answer 1

Answer:

C.) $K_a = \frac{[H^+][H_2PO_4^-]}{[H_3PO_4]}$

Explanation:

The general structure for a Ka expression is:

$K_a = \frac{[H^+][A^-]}{[HA]}$

In this expression,

-----> Ka = equilibrium constant

-----> [A⁻] = base

-----> [HA] = acid

The products are in the numerator and the reactants are in the denominator. In this case, H₃PO₄ serves as an acid and H₂PO₄⁻ serves as a base.

As such, the equilibrium expression is:

$K_a = \frac{[H^+][H_2PO_4^-]}{[H_3PO_4]}$