A solution contains . If is added to make the total concentration , what is the final ? () — Ionic Equilibrium Chemistry Question
Question
A solution contains $0.1 \text{ M } H_2S$. If $HCl$ is added to make the total $H^+$ concentration $0.1 \text{ M}$, what is the final $[S^{2-}]$? ($K_{a1} = 10^{-7}, K_{a2} = 10^{-14}$)
Answer: B
💡 Solution & Explanation
For $H_2S$, overall $K = K_1 K_2 = [H^+]^2[S^{2-}]/[H_2S] = 10^{-21}$. Since $H^+$ is fixed at 0.1 M by HCl and $[H_2S] \approx 0.1 \text{ M}$, $(0.1)^2[S^{2-}] / (0.1) = 10^{-21} \implies [S^{2-}] = 10^{-20} \text{ M}$.
💬Ask on WhatsApp →
Still have doubts about this question?
Send it to our AI chemistry tutor on WhatsApp — gets answered in minutes