The following figure represents solutions at various stages of the titration of a weak acid, HA, with NaOH. (The Na+ ions and water molecules have been omitted for clarity.) To which of the following regions of the titration curve does each drawing correspond: (b) after addition of NaOH but before the equivalence point? [Section 17.3]
Ch.17 - Additional Aspects of Aqueous Equilibria
Chapter 17, Problem 6d
Match the following descriptions of titration curves with the diagrams: (d) strong base added to polyprotic acid. [Section 17.3]

1
Identify the characteristics of a titration curve for a strong base added to a polyprotic acid.
Understand that a polyprotic acid can donate more than one proton, leading to multiple equivalence points in the titration curve.
Recognize that each equivalence point corresponds to the complete neutralization of one of the acidic protons.
Note that the pH at each equivalence point will increase as more protons are neutralized, and the curve will have multiple buffering regions.
Look for a titration curve with multiple steps or plateaus, each representing the neutralization of a different proton from the polyprotic acid.

Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
1mWas this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Titration Curves
Titration curves graphically represent the pH changes that occur during the titration of an acid or base. They illustrate how the pH of a solution changes as a titrant is added, showing distinct regions such as the initial pH, buffer regions, and equivalence points. Understanding these curves is essential for interpreting the behavior of acids and bases during titration.
Recommended video:
Guided course
Acid-Base Titration Curves
Polyprotic Acids
Polyprotic acids are acids that can donate more than one proton (H+) per molecule in a stepwise manner. Each dissociation step has its own equilibrium constant, leading to multiple equivalence points in a titration curve. Recognizing the characteristics of polyprotic acids is crucial for predicting the shape of their titration curves and understanding the pH changes at each stage.
Recommended video:
Guided course
Polyprotic Buffers
Equivalence Point
The equivalence point in a titration is the stage at which the amount of titrant added is stoichiometrically equivalent to the amount of substance being titrated. At this point, the reaction between the acid and base is complete, resulting in a significant change in pH. Identifying the equivalence point is vital for determining the concentration of the unknown solution and interpreting the titration curve accurately.
Recommended video:
Guided course
At the Equivalence Point
Related Practice
Textbook Question
1274
views
Textbook Question
Match the following descriptions of titration curves with the diagrams: (a) strong acid added to strong base. [Section 17.3]
544
views
Textbook Question
The following graphs represent the behavior of BaCO3 under different circumstances. In each case, the vertical axis indicates the solubility of the BaCO3 and the horizontal axis represents the concentration of some other reagent. (a) Which graph represents what happens to the solubility of BaCO3 as HNO3 is added? [Section 17.5]
699
views
Textbook Question
Ca1OH22 has a Ksp of 6.5 * 10-6. (b) If 50 mL of the solution from part (a) is added to each of the beakers shown here, in which beakers, if any, will a precipitate form? In those cases where a precipitate forms, what is its identity? [Section 17.6]
737
views