Chapter 16: Reactions Between Acids and Bases Flashcards Preview

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Flashcards in Chapter 16: Reactions Between Acids and Bases Deck (43):
1

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

quantity

2

analyte: substance whose concentration is

being determined

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titrant is the substance added to

react with the analyte

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

unknown []

5

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

pH range

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

color change; endpoint

7

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

amount of titrant that is added

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

each mole of acid present in the sample

9

inflection point: point at which pH

changes most rapidly

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

sharp change

11

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

stoichiometry, concentrations, volumes

12

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

resist changes in pH

13

strong acids and bases cannot be used as

buffers

14

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

acid; salt; base; salt

15

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

1/Ka; large; completion

16

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

pKa for the acid

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buffers are most effective in the range of

pKa +- 1

18

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

100 times the Ka or Kb

19

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

.1 to 1.0 M

20

concentrated buffers are generally more ... than dilute buffers

effective

21

the effectiveness of a buffer is measured by

buffer capacity

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

one liter of buffer by one unit

23

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

anion of the acid; strong base

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

base; strong acid

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

acid present, not whether it is strong or weak

26

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

excess OH- determines the pH of solution

27

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

pKa

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the pH at the equivalence point is not 7.0 unless

both the acid and the base are strong

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

color

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

end point; equivalence point

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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)

abruptly; visible; perturb

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

weak acid-base conjugate pairs

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HIn + H2O H3O+ + In-
Kin=

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

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

acid; base

35

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

equivalence point

36

polyprotic acids provide more than one ... when they ionize

proton

37

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

more than 1000

38

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

mixture of weak acids

39

amphoteric species have the properties of both

acids and bases

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 ...

Ka; Kb; acidic; basic

41

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

acid

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solubility of a precipitate increases in the presence of a

complexing agent

43

additive reactions --> ... Ks to find overall equilibrium constants

multiply