## Chemistry 10th Edition

1. Identify the conjugate acid-base pairs for each solution. (It has to be a weak acid-base one.) (a) $CN^-$ and $HCN$; (b) Doesn't have one. (c) $NH_3$ and $N{H_4}^+$; (d) Doesn't have one. Since the solutions have similar concentrations for both acids and bases, (a) and (c) are buffers. (b) The common ion here is $Na^+$, which isn't a significant electrolyte. (c) The common ion here is $OH^-$, which is strong, so the solution can't be a buffer.