Ch. 18: Aqueous Ionic Equilibrium

Question 1

buffer

Answer 1

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.

Question 2

common ion effect

Answer 2

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.

Question 3

Henderson-Hasselbalch equation

Answer 3

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 = pK_a + log [base]/[acid].

Question 4

buffer capacity

Answer 4

The amount of acid or base that we can add to a buffer without causing a large change in pH.

Question 5

acid-base titration

Answer 5

A basic (or acidic) solution of unknown concentration reacts with an acidic (or basic) solution of known concentration.

Question 6

indicator

Answer 6

A substance whose color depends on the pH.

Question 7

equivalence point

Answer 7

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.

Question 8

endpoint

Answer 8

The point where the indicator changes color to determine the equivalence point