A aqueous solution of the salt NaA contains the conjugate base A⁻ of the weak acid HA

CHEMISTRY · Single correct · A Level · Chemistry · Acids and bases · Acids and bases

Problem

0.25\,\text{M}

aqueous solution of the salt NaA contains the conjugate base A⁻ of the weak acid HA, for which

K_a = 4.0 \times 10^{-4}

at 25 °C. What is the pH of the NaA solution at 25 °C? (Assume that the activity coefficients are 1.) (a)

8.40

(b)

8.90

(c)

5.10

(d)

7.00