Unformatted text preview: equilibrium-constant expression for the dissociation of acetic acid.
[HC2 H3O2 ]
− [C2 H 3O 2 ] = [H + ]
Ka After the addition of the H+, the ratio in buffer 1 must have been greater
than the corresponding ratio in buffer 2, as evidenced by their respective pH
values. Thus a greater proportion of the C2H3O2− in buffer 1 must have
reacted with the added H+ compared to the proportion that reacted in
buffer 2. The difference between these proportions means that the original
concentrations of HC2H3O2 and C2H3O2− had to be smaller in buffer 1 than
in buffer 2. One point is earned for a
correct answer involving
better buffering capacity
or relative amount of base
(acetate ion). © 2007 The College Board. All rights reserved.
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2007 SCORING GUIDELINES (Form B)
Question 5 (continued)
(iii) Explain why the pH of buffer 1 is the same as the pH of buffer 2 before 0.10 mol of HCl is...
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This note was uploaded on 10/01/2009 for the course OC 9876 taught by Professor Dq during the Spring '09 term at UC Merced.
- Spring '09