AP Chemistry Flashcards: Acid-Base Titrations
Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026
Review key ideas with interactive flashcards. This set includes 14 cards to help you master important concepts.
Why is the pH at the equivalence point of a weak base-strong acid titration acidic?
The conjugate acid of the weak base is present at the equivalence point and hydrolyzes water, producing hydronium ions (H3O+) and resulting in an acidic pH.
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Why is the pH at the equivalence point of a weak base-strong acid titration acidic?
The conjugate acid of the weak base is present at the equivalence point and hydrolyzes water, producing hydronium ions (H3O+) and resulting in an acidic pH.
Why is the pH at the equivalence point of a weak acid-strong base titration basic?
The conjugate base of the weak acid is present at the equivalence point and hydrolyzes water, producing hydroxide ions (OH-) and resulting in a basic pH.
What causes the multiple equivalence points on a titration curve for a polyprotic acid?
Each equivalence point corresponds to the complete neutralization of one of the acidic protons of the polyprotic acid.
What is the pH at the equivalence point of a strong acid-strong base titration?
The pH at the equivalence point for a strong acid-strong base titration is neutral (pH = 7) because the resulting salt does not hydrolyze water.
How can you determine the pKa of a weak acid from its titration curve?
The pKa of a weak acid can be determined from the titration curve by finding the pH value at the half-equivalence point, as pH = pKa at this point.
On a titration curve, how would you identify the major species present at the first equivalence point of a diprotic acid (H2A) titration?
At the first equivalence point, all of the H2A has been converted to its conjugate base, so the major species is the intermediate form, HA-.
On a titration curve for a diprotic acid, what does the first half-equivalence point signify?
The first half-equivalence point signifies the point where pH = pKa1 for the first acidic proton.
What three key pieces of information can be determined from a polyprotic acid's titration curve?
A polyprotic acid's titration curve can be used to determine the number of acidic protons, the pKa associated with each proton, and the major species present at any point in the titration.
How is the equivalence point used to find an analyte's concentration?
Since moles of titrant equal moles of analyte at the equivalence point, the known volume and concentration of the titrant can be used to calculate the unknown concentration of the analyte.
What is the half-equivalence point in a weak acid titration?
The half-equivalence point is the point where the concentration of the weak acid ([HA]) equals the concentration of its conjugate base ([A-]).
What is a titration curve?
A titration curve is a graph that plots the pH of a solution versus the volume of titrant added, which is useful for summarizing the results from a controlled acid-base reaction.
What is the equivalence point in a monoprotic titration?
The equivalence point is the point in a titration where the moles of titrant added are stoichiometrically equal to the original moles of the analyte.
How do titration results relate to the properties of the solution and its components?
Titration results, shown on a curve, reveal properties like the analyte's concentration (from equivalence point) and its acid strength/pKa (from half-equivalence point).
What is the key chemical relationship at the half-equivalence point of a weak acid/base titration?
At the half-equivalence point, the concentration of the weak acid is equal to the concentration of its conjugate base, or [HA] = [A-].