Which of the following statements is true when comparing the following two hypothetical buffer solutions? (Assume HA is a weak acid.) (See choices in answer).

Buffer A: #0.250# mol #HA# and #0.500# mol #A^-# in
#1 L# of pure water

Buffer B: #0.030# mol #HA# and #0.025# mol #A^-# in
#1 L# of pure water

A. Buffer A is more centered and has a higher buffer capacity than Buffer B.
B. Buffer A is more centered, but has a lower buffer capacity than Buffer B.
C. Buffer B is more centered, but has a lower buffer capacity than Buffer A.
D. Buffer B is more centered and has a higher buffer capacity than Buffer A.
E. There is not enough information to compare these buffers with respect to both
centeredness and capacity

A buffer is centered if it has equal amounts of weak acid & conjugate base or weak base & conjugate acid. This makes for the most ideal buffer systems because a centered buffer could absorb equal amounts of additional acid or base.

Buffer capacity is the relative concentration of the
#("conjugated base"/"weak acid")# or #("weak base"/"conjugate acid")#.

More concentrated buffered are better at withstanding extra acid or base.

In the buffers given above, Buffer B is more centered in that the amounts of weak acid and conjugate base are closer to equal. Since the conjugate base in Buffer A is more concentrated than Buffer B, it can better withstand additions of acid or base.