Question 22.8: GRADED Calculate equilibrium constants for the two acid-base...

GRADED

Calculate equilibrium constants for the two acid-base reactions above.

ⓐ CH_{3}NH_{2}(aq)  +  H^{+}(aq)  →  CH_{3}NH_{3}^{+}(aq)

ⓑ CH_{3}NH_{2}(aq)  +  CH_{3}COOH(aq)  \rightleftharpoons   CH_{3}NH_{3}^{+}(aq)  +  CH_{3}COO^{-}(aq)

ⓐ

STRATEGY

1. Note that the given equation is the reverse of the equation for the dissociation of a weak acid.
2. Find K_{a} for CH_{3}NH_{3}^{+} in Appendix 1 and use the reciprocal rule (Chapter 12).

ⓑ

STRATEGY

1. Break up the given equation into two reactions
CH_{3}NH_{2}  \rightleftharpoons  CH_{3}NH_{3}^{+}  (1)
CH_{3}COOH  \rightleftharpoons  CH_{3}COO^{-} (2)
2. Find K for each reaction
3. Combine the two equations and their Ks. Apply the Rule of Multiple Equilibria (Chapter 12).