Answer to Question #116782 in General Chemistry for Jeanne

Question

Determine the Ka of an acid whose 1.56 M Solution has a pH of 1.98

Answer 1

1)

$$pH = -log[H^+]$$

$$[H^+] = 10^{-pH} = 10^{-1.98} = 0.0105$$

2)

$$k_a = {[H^+][A^-] \over [HA]} = {(0.0105)^2 \over 1.56} = 7.07 * 10^{-5}$$