Equal volumes of 0.10 M NH₃ (K_b = 1.8 × 10^-5)and 0.10 M HCN (K_a = 4.9 × 10^-10)are mixed together.Will the resulting solution be acidic,basic,or neutral?

Question

Quizplus · Accepted Answer

HCN is a weak acid with a pKa value of 9.2, meaning that it dissociates only slightly in water to form H+ and CN- ions. NH4+ is the conjugate acid of a weak base NH3, with a pKa value of 9.3, meaning that it will only slightly dissociate in water to form NH3 and H+ ions. The addition of the NH4+ to the solution will cause a shift in the equilibrium towards the formation of more NH3 and H+ ions. Since NH3 is a weak base, it will not completely neutralize the H+ ions, resulting in a basic solution.

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