Analytical Chemistry Chapter 7

Question 1

depend on a chemical reaction of the analyte
with a standard reagent.

Answer 1

neutralization titrations

Question 2

The _______ is indicated by a chemical indicator or an instrumental measurement

Answer 2

point of chemical equivalence

Question 3

The standard solutions used in neutralization titrations are ________ because these substances react more completely with an analyte than do weak acids and bases, and as a result, they produce sharper end points.

Answer 3

strong acids or strong
bases

Question 4

Standard solutions
of acids are prepared by diluting concentrated:

Answer 4

hydrochloric, perchloric, or sulfuric acid

Question 5

Seldom used because its oxidizing properties offer the potential for undesirable side reactions.

Answer 5

Nitric acid

Question 6

_______ are potent
oxidizing agents and are very hazardous.

Answer 6

Hot concentrated perchloric and sulfuric acids

Question 7

are usually prepared from solid sodium, potassium,
and occasionally barium hydroxides.

Answer 7

Standard solutions of bases

Question 8

The pH interval over which a given indicator exhibits a color change is influenced by:

Answer 8

temperature
ionic strength of the medium
presence of organic solvents and colloidal particles.

Question 9

The hydronium ions in an aqueous solution of a strong acid have two sources:

Answer 9

(1) the reaction of the acid with water.
(2) the dissociation of water itself.

Question 10

is a mixture of a weak acid and its conjugate base or weak base and its conjugate acid that resists change in pH of a solution.

Used in all types of chemistry whenever it is desirable to maintain the pH of the solution at a constant and predetermined level.

Answer 10

Buffer

Question 11

Whenever a weak acid is titrated with a strong acid or a weak base with a strong acid, a _______ consisting of a conjugate acid/base pair is formed.

Answer 11

buffer solution

Question 11

Three types of calculations must be
done in order to construct the hypothetical curve for titrating a solution of a strong acid
with a strong base.

Each of these types corresponds to a distinct stage in the titration:

Answer 11

(1) preequivalence
(2) equivalence
(3) postequivalence.

Question 12

Frequently encountered in biological literature and biochemical text. Obtained by expressing each term in the equation in the form of its negative logarithm and inverting the concentration ratio to keep all signs positive.

Answer 12

Henderson-Hasselbalch Equation

Question 13

defined as the number of moles of a strong acid or a strong base that causes 1.00 L of the buffer to undergo a 1.00-unit change in pH.

number of moles of strong acid or strong bases that causes one liter of the buffer to change pH by one unit.

Answer 13

Buffer Capacity

Question 14

__________ for strong and weak acids are identical just slightly beyond the equivalence point. The same is true for strong and weak bases.

Answer 14

Titration curves

Question 15

Since the principal solute species at the equivalence point is HCN, the pH is ________

Answer 15

acidic

Question 16

When titrating a weak base, use an indicator with an ______.

When titrating a weak acid, use an indicator with a ________.

Answer 16

acidic transition range

basic transition range

Question 16

The changes in composition that occur while a solution of
a weak acid or a weak base is being titrated. These changes can be visualized by plotting the relative equilibrium concentration of the weak acid as well as the relative equilibrium concentration of the conjugate base as functions of the pH of the
solution. These relative concentrations are called _______

Answer 16

alpha values

Question 16

is an amino acid with two carboxyl groups. It can be combined with phenylalanine to make the artificial sweetener aspartame, which is sweeter and less fattening than ordinary sugar.

Answer 16

Aspartic acid