15.4 Titrations

A solution of unknown concentration

analyte

A solution of known concentration

titrant

The point in the titration where the proportions of analyte and titrant present in the reaction mixture match those required from the stoichiometry of the chemical reaction

• In acid-base: moles of H+ = moles of OH-

equivalence point

The indicator changes color to signal the completion of the reaction/titration

endpoint

weak acid and strong base titration

In a weak acid / strong base titration, the initial pH is that of the _________.

weak acid

What is the region before the equivalence point called?

buffer zone (note: this means that both weak acid/conjugate base or weak base/conjugate acid present)

What is significant about the half-equivalence point?

At the half-equivalence point, pH = pK_a

weak base and strong acid titration

polyprotic acid titration (note: if the Ka value is too small or if the sequential Ka values are too close to each other, then the titration curve will become too flat to identify the equivalence points)

A general rule of thumb for indicators is that they change colors when the pH is ______.

pK_a ± 1