Chapter 16

Question 1

The simplest acid–base equilibria are those in which

Answer 1

a weak acid or a weak base reacts with water.

Question 2

The equilibrium constant for the reaction of a weak acid with water is called the

Answer 2

• Acid−ionization constant (or acid−dissociation constant), Ka
• Liquid water is not included in the equilibrium constant expression.

Question 3

The equilibrium concentration of the acid is most often

Answer 3

([HA]0 – x).

If x is much, much less than [HA]0, we can assume that subtracting x makes no difference to [HA]

This is a valid assumption when the ratio of [HA]0to Ka is > 103. If it is not valid, you must use the quadratic equation to solve the problem.

Question 4

A polyprotic acid has

Answer 4

more than one acidic proton—for example, H2SO4, H2SO3, H2CO3, H3PO4

Question 5

The simplest acid–base equilibria are those in which

Answer 5

a weak acid or a weak base reacts with water.

Question 6

The equilibrium constant for the reaction of a weak base with water is called the

Answer 6

base−ionization constant, Kb

Question 7

Salt Solutions

Answer 7

We will look at the cation and the anion separately, and then combine the result to determine whether the solution is acidic, basic, or neutral

Question 8

The conjugate acid of a strong base is very weak and does not react with water. It is therefore considered to be

Answer 8

neutral

Question 9

The conjugate base of a strong acid is very weak and does not react with water. It is therefore considered to be

Answer 9

neutral

Question 10

hydrolysis

Answer 10

The hydrolysis equilibrium constant can be used in problems to determine the pH of a salt solution. To use the hydrolysis equilibrium, we need to compute the K value for it.

Question 11

Common−Ion Effect

Answer 11

The common−ion effect is the shift in an ionic equilibrium caused by the addition of a solute that takes part in the equilibrium.

Question 12

buffers

Answer 12

A buffer solution is characterized by the ability to resist changes in pH when limited amounts of acid or base are added to it.

A buffer is made by combining a weak acid with its conjugate base or a weak base with its conjugate acid.

Question 13

Henderson—Hasselbalch Equation

Answer 13

Buffers at a specific pH can be prepared using the Henderson−Hasselbalch Equation.

Buffers are prepared from a conjugate acid−base pair in which the ionization is approximately equal to the desired H3O+ concentration.

Question 14

Acid–Base Titration

Answer 14

An acid–base titration is a procedure for determining the amount of acid (or base) in a solution by determining the volume of base (or acid) of known concentration that will completely react with it

Question 15

Acid–base titration curve

Answer 15

a plot of the pH of a solution of acid (or base) against the volume of added base (or acid). Such curves are used to gain insight into the titration process. You can use the titration curve to choose an indicator that will show when the titration is complete.

Question 16

equivalence point

Answer 16

is the point in a titration when a stoichiometric amount of reactant has been added

Question 17

When solving problems in which an acid reacts with a base, we first need to determine the

Answer 17

the limiting reactant. This requires that we use moles in the calculation.

The next step is to review what remains at the end of the reaction. In the case of a strong acid and a strong base, the solution is neutral.

When a weak acid or weak base is involved, the product is a salt. After finding the salt concentration, we use a hydrolysis equilibrium to find the pH