AP Chemistry 8.5: Acid-Base Titrations

Practice AP Chemistry questions on reading and sketching titration curves, finding pKa and concentration, locating equivalence points, and selecting indicators.

Exam points

Explain how thermodynamic quantities describe energy, entropy and spontaneity in chemical reactions.
Apply Gibbs energy and equilibrium relationships to predict reaction feasibility under changing conditions.

[Maximum number: 1]

Answer the following questions about ascorbic acid (vitamin C).

Ascorbic acid, HAsc (a q), acts as a weak acid, as shown in the equation.

\mathrm{HAsc}(a q)+\mathrm{H}_{2} \mathrm{O}(l) \rightleftarrows \mathrm{H}_{3} \mathrm{O}^{+}(a q)+\mathrm{Asc}^{-}(a q)

The following titration curve was produced when a 10.0 mL sample of HAsc (a q) was titrated

using $0.0550 M \mathrm{NaOH}(a q)$ .

Figure for Question 8.5.A—Explain results from the titration of a mono- or polyprotic acid or base solution, in relation to the properties… question 1 — AP Chemistry

From the titration curve, determine the approximate $\mathrm{p} K_{a}$ of ascorbic acid.

(ii) For the correct $\mathrm{p} K_{a}$ :

4.1 (acceptable range: 4.0-4.3)

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8.5.A—Explain results from the titration of a mono- or polyprotic acid or base solution, in relation to the properties… question 1