Question

Which describes the "buffer" region in a titration curve?

a. flat portion of the curve long after the equivalence point has been reached
b. steep portion of the curve immediately after the equivalence point
c. flat portion of the curve just before the equivalence point
d. concave portion of the cure immediately after the addition of titrant

Answer 1

The buffer region in a titration curve is the flat portion just before the equivalence point where a buffer solution is formed and resists changes in pH.

Step-by-step explanation:

The "buffer" region in a titration curve is described as the flat portion of the curve just before the equivalence point. This region typically corresponds to the point where the pH does not change significantly with the addition of the titrant because a buffer solution, which resists changes in pH, is formed. In a titration curve, this buffer region usually occurs when a weak acid reacts with a strong base, and it is observable as a nearly flat line around the midpoint of the titration curve. This is because the weak acid (HA) partly dissociates into H+ and A- (its conjugate base), and the addition of more base to the system does not significantly change the pH until the buffering capacity is exceeded.

Answer 2

The 'buffer' region in a titration curve is the flat portion just before the equivalence point which corresponds to the formation of a buffer and shows minimal pH change with added titrant.

Step-by-step explanation:

The "buffer" region in a titration curve describes the nearly flat portion of the curve that occurs when titrating a weak acid with a strong base and is located around the midpoint of the titration. This region corresponds to the formation of a buffer and exhibits the smallest change in pH per increment of added titrant. Specifically, it can be described as the portion of the curve just before the equivalence point where the pH of the solution is determined by the equilibrium for dissociation of the weak acid (Ka) and after the midpoint where it's determined by the equilibrium for the reaction of the conjugate base with water. Therefore, the correct description for the "buffer" region in a titration curve is (c) flat portion of the curve just before the equivalence point.