A titration curve is a graph of a solution's pH versus the volume of titrant added; its steep vertical region marks the equivalence point, where the moles of titrant exactly consume the moles of analyte (AP Chem Topic 4.6, learning objective 4.6.A).
A titration curve is the picture a titration draws as it happens. Plot pH on the y-axis and volume of added titrant on the x-axis, and you get a curve with a distinctive shape. It starts relatively flat (pH changes slowly as you add titrant), then shoots nearly straight up (or down, if you're adding acid to base) in a steep vertical region, then levels off again. The midpoint of that steep jump, the inflection point, is the equivalence point. That's the exact volume where the analyte has been completely consumed by the titrant.
The whole reason titrations exist is captured in essential knowledge for 4.6.A. The titrant has a known concentration, it reacts specifically and quantitatively with the analyte, and the equivalence point tells you exactly how many moles of titrant it took to use up the analyte. The curve is just the most reliable way to find that point. Instead of trusting your eyes and an indicator's color change (the end point), you read the volume at the center of the steep rise and do stoichiometry from there.
Titration curves live in Unit 4: Chemical Reactions, Topic 4.6 (Introduction to Titration), supporting learning objective 4.6.A, which asks you to identify the equivalence point from the amounts of titrant and analyte. In Unit 4 the math is pure stoichiometry. Read the equivalence-point volume off the curve, convert to moles of titrant using molarity, use the mole ratio, and solve for the unknown concentration of the analyte. This is one of the highest-yield lab-based skills in the course. The same graph comes back with much more detail in Unit 8, where you'll analyze the shape of the curve for weak acids and bases, buffers, and pKa. Learn to read it now and Unit 8 gets dramatically easier.
Keep studying AP Chemistry Unit 4
Equivalence Point (Unit 4)
The equivalence point is the single most important feature on a titration curve. It sits at the inflection point, the center of the steep vertical region. Everything quantitative in a titration problem flows from reading this volume correctly.
End Point and pH Indicators (Unit 4)
The end point is what you actually observe in lab, the moment the indicator changes color. A well-chosen indicator changes color within the steep region of the curve, so the end point lands close to the true equivalence point. The curve shows you why indicator choice matters.
Molarity and Standard Solutions (Unit 4)
The titrant is a standard solution with a precisely known molarity. The curve gives you a volume, molarity converts that volume to moles, and the balanced equation's mole ratio gets you to the unknown analyte concentration. The graph and the math are two halves of one calculation.
Conjugate Acids and Bases (Unit 8)
In Unit 8, titration curves level up. The flat region before the equivalence point of a weak acid titration is a buffer made of the acid and its conjugate base, and the pH at the half-equivalence point equals the acid's pKa. Same graph, deeper analysis.
Titration curves show up in both multiple choice and free response, almost always asking you to read the graph and then calculate. A classic stem gives you a curve with a steep rise at a specific volume, like titrating 20.0 mL of unknown HCl with 0.50 M NaOH and a vertical jump centered at 24.0 mL, then asks for the molarity of the acid. The move is always the same. Take the equivalence-point volume, find moles of titrant (0.0240 L × 0.50 M = 0.0120 mol), apply the 1:1 mole ratio, and divide by the analyte volume to get 0.60 M. On free-response questions, titrations appear inside larger lab scenarios. The 2024 long FRQ used an NaOH titration of lactic acid, and the 2025 long FRQ built a question around titrating ascorbic acid. You may also be asked conceptual questions, like what the inflection point indicates (the equivalence point) or what the flatter regions represent (gradual pH change before and after the steep jump).
The equivalence point is a stoichiometric fact. It is the exact volume where moles of titrant equal what's needed to consume the analyte, and it sits at the inflection point of the titration curve. The end point is an observation, the moment the indicator visibly changes color. They're designed to be close but they are not the same thing. On the AP exam, do your calculations from the equivalence point on the curve, and use 'end point' only when describing what you'd see in lab.
A titration curve plots pH on the y-axis against volume of titrant added on the x-axis.
The equivalence point is located at the inflection point, the middle of the curve's steep vertical region, where the analyte is completely consumed by the titrant.
The end point is the observed indicator color change, which approximates but does not define the equivalence point.
To find an unknown concentration, read the equivalence-point volume from the curve, convert to moles of titrant using its molarity, apply the mole ratio, and divide by the analyte's volume.
The flatter regions of the curve show gradual pH change before and after the steep jump at equivalence.
Titration curves return in Unit 8, where the buffer region and half-equivalence point let you find a weak acid's pKa.
It's a graph showing how the pH of a solution changes as titrant is added, with pH on the y-axis and titrant volume on the x-axis. Its steep vertical region pinpoints the equivalence point, which is the basis for finding an unknown concentration (Topic 4.6, learning objective 4.6.A).
No. The equivalence point is the stoichiometric point where moles of titrant exactly consume the analyte, found at the curve's inflection point. The end point is when the indicator changes color, an observable signal chosen to fall close to the equivalence point.
Look for the steep, nearly vertical section of the curve and find its center, the inflection point. The volume at that point is the equivalence-point volume, the number you plug into your stoichiometry.
Read the equivalence-point volume, multiply by the titrant's molarity to get moles of titrant, use the balanced equation's mole ratio to get moles of analyte, then divide by the analyte's volume. For 20.0 mL of HCl titrated with 0.50 M NaOH reaching equivalence at 24.0 mL, that gives 0.0120 mol HCl and a concentration of 0.60 M.
They're the regions where pH changes slowly as titrant is added, before and after the steep jump. In Unit 4 you just need to recognize them as gradual pH change; in Unit 8, the flat region before equivalence in a weak acid titration becomes the buffer region.