Consider the buffer pair, NH₄Cl/NH₃. What can be stated about the relative proportions of this buffer pair if the pH of an aqueous solution of this pair is adjusted to 12.00 and the p K _a for NH₄⁺ equals 9.25?

Question

Quizplus · Accepted Answer

At a pH of 12, the solution is very basic and the concentration of H+ ions is very low. Therefore, the buffer pair is in its deprotonated form, with NH₄⁺ and NH₃ both present. The p K_a of NH₄⁺ is 9.25, which means that at pH 9.25, the concentration of NH₄⁺ and NH₃ will be equal. At higher pH values, the concentration of NH₃ will be greater than that of NH₄⁺, so choice B is correct.

Consider the Buffer Pair, NH4Cl/NH3

Consider the Buffer Pair, NH₄Cl/NH₃