Equal volumes of 0.010 M HCl are separately added to two beakers: one contains 1.00 L…
CHEMISTRY · Single correct · A Level · Chemistry · Acids and bases · Acids and bases
Problem
Equal volumes of 0.010 M HCl are separately added to two beakers: one contains 1.00 L of pure water (initial pH = 7.00), and the other contains 1.00 L of a solution that is 0.10 M in both CH₃COOH and CH₃COO⁻. Which of the following predictions about the resulting pH changes is most accurate?
(a) The buffer’s pH will rise slightly while the pure water’s pH falls, because CH3COO− removes nearly all of the added H+.
(b) Both solutions will experience about the same decrease in pH because each receives the same concentration of added H+.
(c) The pH of the pure water will drop by roughly 2 units, whereas the buffer’s pH will drop by far less than 1 unit because CH3COO− neutralizes most of the added H+.
(d) The buffer’s pH will fall more than the water’s pH because the weak acid component releases additional H+ into the solution.