Final answer:
The correct answer is option C. A titration curve with an initial pH of 13.00, an equivalence point at 7.0, and a nearly vertical middle section corresponds to a weak acid titrated by strong base.
Step-by-step explanation:
The titration curve described, with an initial pH of 13.00, an equivalence point at 7.0, and a relatively long, nearly vertical middle section, is characteristic of the titration of a weak acid by a strong base. Let's break down the key features.
The initial pH of 13.00 suggests a highly basic solution, which aligns with the addition of a strong base. As the strong base is added to the weak acid, the pH rises steeply due to the neutralization reaction, forming water and a salt. The equivalence point, where the amount of acid is stoichiometrically equal to the added base, occurs at a pH of 7.0.
The relatively long, nearly vertical middle section of the curve corresponds to the buffer region. In this phase, the weak acid is partially neutralized, resulting in the formation of a buffer solution. Buffers resist changes in pH, leading to a gradual change in pH despite the addition of more base.
This behavior is consistent with the titration of a weak acid by a strong base, making option (c) the correct choice. The titration curve's characteristics provide insights into the nature of the reacting species and their concentrations throughout the titration process.