AP Chemistry — Unit 8: Acids and Bases
Strong acid–strong base titration
A titration follows how pH changes as titrant is added to an analyte. In a strong acid–strong base titration the only reaction that matters is H⁺ + OH⁻ → H₂O, so the pH at any point is decided by whichever ion is left over once neutralization is done. Drag the slider below to add 0.100 M HCl to 10.0 mL of 0.100 M NaOH and watch the curve build.
What to take away: the pH barely moves through most of the titration, because the leftover strong base is still concentrated enough to dominate. Near the equivalence point — where moles of added H⁺ equal the initial moles of OH⁻ — a single drop wipes out the last of the excess ion, and the pH falls almost vertically. For a strong acid–strong base pair at 25 °C the equivalence point sits at pH 7.00, because the only species left are water and the spectator ions Na⁺ and Cl⁻. That is not true for weak acid–strong base titrations, where the conjugate base makes the equivalence point basic.