For which of the following 0.10 M diprotic acids would the second dissociation affect the pH significantly? A)H₂A;K_a1 = 4.2 $\times$ 10^-²,K_a2 = 1.8 $\times$ 10^-⁷ B)H₂B;K_a1 = 2.4 $\times$10^-⁴,K_a2 = 6.1 $\times$ 10^-⁸ C)H₂C;K_a1 = 1.3 $\times$ 10^-⁴,K_a2 = 5.2 $\times$ 10^-⁹ D)H₂D;K_a1 = 1.8 $\times$ 10^-³,K_a2 = 9.3$\times$ 10^-⁴ E)The second dissociation never affects the pH significantly.

Question

Quizplus · Accepted Answer

The second dissociation affects the pH significantly when the second dissociation constant (Ka2) is greater than 10^-6. In option D, Ka2 = 9.3 × 10^-15 which is greater than 10^-6. Therefore, the second dissociation will affect the pH significantly for this diprotic acid. The other options have Ka2 values less than 10^-6, indicating that the second dissociation will not significantly affect the pH.

For Which of the Following 0 ×\times× 10-2,Ka2 = 1 ×\times× 10-7 B)H2B;Ka1 = 2

For Which of the Following 0 $\times$ 10^-²,K_a2 = 1 $\times$ 10^-⁷
B)H₂B;K_a1 = 2