Ch. 18: Aqueous Ionic Equilibrium Flashcards
buffer
It resists pH change by neutralizing added acid or added base. It contains either significant amounts of both a weak acid and its conjugate base or significant amounts of both a weak base and its conjugate acid. Weak acid neutralizes added base and the weak base neutralizes added acid.
common ion effect
The tendency for a common ion to decrease the solubility of an ionic compound or to decrease the ionization of a weak acid or weak base.
Henderson-Hasselbalch equation
The equation used to easily calculate the pH of a buffer solution from the inital concentrations of the buffer components, assuming that the “x is small” approcimation is valid; pH = pKa + log [base]/[acid].
buffer capacity
The amount of acid or base that we can add to a buffer without causing a large change in pH.
acid-base titration
A basic (or acidic) solution of unknown concentration reacts with an acidic (or basic) solution of known concentration.
indicator
A substance whose color depends on the pH.
equivalence point
The point in the titration when the number of moles of base is stoichiometrically equal to the number of moles of acid. The titration is complete. Neither reactant is in excess and the number of moles of the reactants are related by the reaction stoichiometry.
endpoint
The point where the indicator changes color to determine the equivalence point