Acid–Base Equilibria (5A) Practice Test

In a renal physiology model, tubular fluid contains an acetate buffer: $\mathrm{CH_3COOH\rightleftharpoons H^+ + CH_3COO^-}$ with $pK_a=4.76$. If the tubule secretes additional $\mathrm{H^+}$ into the fluid, which statement best describes the immediate chemical response of the buffer pair?

To test buffer range, a lab prepares a 0.10 M buffer of benzoic acid/benzoate with $pK_a=4.20$ at pH 4.20. The experiment requires pH stability between 3.2 and 5.2. Based on the passage, which conclusion about the buffer system is most consistent?