Chapter 16: Reactions Between Acids and Bases

Question 1

titration: a procedure for the determination of the … of one substance by the addition of a measured amount of a second substance

Answer 1

quantity

Question 2

analyte: substance whose concentration is

Answer 2

being determined

Question 3

titrant is the substance added to

Answer 3

react with the analyte

Question 4

(basic procedure for acid-base titrations) 1) a known volume of an acid of … is placed in a flask

Answer 4

unknown []

Question 5

(basic procedure for acid-base titrations) 2) an indicator solution that changes color in a particular … is added to the acid

Answer 5

pH range

Question 6

(basic procedure for acid-base titrations) 3) a standard solution of base is added until a … occurs, called the …

Answer 6

color change; endpoint

Question 7

a titration curve is a graph of the pH of a solution as a function of the

Answer 7

amount of titrant that is added

Question 8

equivalence point: point in the titration when exactly one mole of base has been added for

Answer 8

each mole of acid present in the sample

Question 9

inflection point: point at which pH

Answer 9

changes most rapidly

Question 10

the titration of a strong acid with a strong base shows a … in pH at the equivalence point

Answer 10

sharp change

Question 11

the titration .., …, and … all influence the equivalence point volume

Answer 11

stoichiometry, concentrations, volumes

Question 12

buffers are solutions that … when either OH- or H+ ions are added

Answer 12

resist changes in pH

Question 13

strong acids and bases cannot be used as

Answer 13

buffers

Question 14

buffered solutions contain either: a weak … and its … or a weak … and its …

Answer 14

acid; salt; base; salt

Question 15

(buffers) keq for neutralization is … meaning that Keq is … and the reaction goes essentially to ..

Answer 15

1/Ka; large; completion

Question 16

pH of buffer solutions is generally limited to the vicinity of the

Answer 16

pKa for the acid

Question 17

buffers are most effective in the range of

Answer 17

pKa +- 1

Question 18

to make an effective buffer, the concentrations of the weak acid and its conjugate base must be at least

Answer 18

100 times the Ka or Kb

Question 19

most pH buffers are made from solutions with concentrations that range from

Answer 19

.1 to 1.0 M

Question 20

concentrated buffers are generally more … than dilute buffers

Answer 20

effective

Question 21

the effectiveness of a buffer is measured by

Answer 21

buffer capacity

Question 22

buffer capacity= the amount of strong acid or base needed to change the pH of

Answer 22

one liter of buffer by one unit

Question 23

acid/salt buffering pairs: salt will contain the …., and the cation of a

Answer 23

anion of the acid; strong base

Question 24

base/salt buffering pairs: the salt will contain the cation of the …, and the anion of a …

Answer 24

base; strong acid

Question 25

the amount of base needed to neutralize an acid depends only on the amount of

Answer 25

acid present, not whether it is strong or weak

Question 26

the titration curves for all the acids are indistinguishable beyond the equivalence point since

Answer 26

excess OH- determines the pH of solution

Question 27

the pH halfway to the equivalence point in the titration of a weak acid is equal to the

Answer 27

pKa

Question 28

the pH at the equivalence point is not 7.0 unless

Answer 28

both the acid and the base are strong

Question 29

indicator: substance that changes … to signal the end of a titration

Answer 29

color

Question 30

an indicator should be chosen such that the … and … are the same

Answer 30

end point; equivalence point

Question 31

indicators should have the following attributes:
change color … as a function of pH
color change should be …
should not … the system (should not consume a large amount of titrant/reactant)

Answer 31

abruptly; visible; perturb

Question 32

indicators are … in which the acid is a different color from the conjugate base

Answer 32

weak acid-base conjugate pairs

Question 33

HIn + H2O H3O+ + In-

Kin=

Answer 33

[H3O+][In-]/[HIn]

Question 34

if pH < pKin, most of the indicator is in the .. form

if pH > pKin, most of the indicator is in the … form

Answer 34

acid; base

Question 35

an indicator should be chosen to change color at or just beyond the

Answer 35

equivalence point

Question 36

polyprotic acids provide more than one … when they ionize

Answer 36

proton

Question 37

successive ionization constants for polyprotic acids get smaller often by a factor of

Answer 37

more than 1000

Question 38

to estimate the pH of a polyprotic acid, treat as if you had a

Answer 38

mixture of weak acids

Question 39

amphoteric species have the properties of both

Answer 39

acids and bases

Question 40

to estimate the pH of a solution of an amphoteric substance, compare … and …. if Ka > Kb, the solution is …. if Kb > Ka, the solution is …

Answer 40

Ka; Kb; acidic; basic

Question 41

the solubility of a salt of a weak acid increases with the addition of

Answer 41

acid

Question 42

solubility of a precipitate increases in the presence of a

Answer 42

complexing agent

Question 43

additive reactions –> … Ks to find overall equilibrium constants

Answer 43

multiply