Chapter 14: Applications of Neutralization Titrations

Question 1

TRUE or FALSE
Solutions of HCl, HClO4, and H2SO4 are stable indefinitely. Restandardization is not required unless evaporation occurs.

Answer 1

TRUE

Question 2

widely used as standard solutions for titrating bases

Answer 2

HCl

Question 3

TRUE or FALSE
solutions of 0.1 M HCl can be boiled for as long as an hour without loss of acid, provided that the water lost by evaporation is periodically replaced

Answer 3

TRUE

Question 4

TRUE or FALSE
0.5 M solutions can be boiled for at least 10 minutes without significant loss

Answer 4

TRUE

Question 5

TRUE or FALSE
Standard solutions of nitric acid is seldom used because of its oxidizing properties

Answer 5

TRUE

Question 6

To obtain most standard acid solutions, a solution of an approximate concentration is first prepared by diluting the concentrated reagent. The diluted acid solution is then standardized against a

Answer 6

primary-standard base

Question 7

TRUE or FALSE
Primary-standard–grade sodium carbonate is available commercially or can be prepared
by heating purified sodium hydrogen carbonate between 270C and 300C
for 1 hour

Answer 7

TRUE

Question 8

is the most common base for preparing standard solutions, although potassium hydroxide and barium hydroxide are also used.

Answer 8

sodium hydroxide

Question 9

The effective concentration of the base is thus diminished by absorption of carbon dioxide, and a systematic error called the

Answer 9

carbonate error

Question 10

TRUE or FALSE
Carbonate ion in standard base solutions decrease the sharpness of end points and is usually removed before standardization.

Answer 10

TRUE

Question 11

is a nearly ideal primary standard. It is a nonhygroscopic crystalline solid with a relatively large molar mass (204.2 g/mol)

Answer 11

KHP (potassium hydrogen phthalate)

Question 12

Several excellent primary standards are available for standardizing bases but most are ___________ that require the use of an indicator with a basic transition range

Answer 12

weak organic acids

Question 13

what bases are used for standardization of acids

Answer 13

sodium carbonate
TRIS (tris-hydroxymethylaminomethane)
sodium tetraborate decahydrate
mercury (II) oxide

Question 14

TRUE or FALSE
In solution as well as in the solid state, the hydroxides of sodium, potassium, and barium
react rapidly with atmospheric carbon dioxide to produce the corresponding carbonate

Answer 14

TRUE

Question 15

TRUE or FALSE
the presence of carbonate ions does not cause a carbonate error provided the same indicator is used for both standardization and analysis, which carbonate does, however, decrease the sharpness of end points and thus is removed before a solution of a base is standardized

Answer 15

TRUE

Question 16

TRUE or FALSE
best method for preparing carbonate-free sodium hydroxide solutions is to vacuum filter the carbonate given its low solubility

Answer 16

TRUE

Question 17

TRUE or FALSE
A tightly capped low-density polyethylene bottle usually provides adequate shortterm
protection against the uptake of atmospheric carbon dioxide

Answer 17

TRUE

Question 18

is an excellent primary standard with a
high molar mass per mole of protons. It is also a strong acid that can be titrated using
virtually any indicator with a transition range between pH 4 and 10.

Answer 18

potassium hydrogen iodate

Question 19

what acids are used in standardizing bases

Answer 19

potassium hydrogen phthalate
benzoic acids
potassium hydrogen iodate

Question 20

are used to determine the many inorganic, organic, and biological species that possess acidic or basic properties

Answer 20

neutralization titrations

Question 21

2 major types of end points

Answer 21

visual end point
potentiometric end point

Question 22

the potential of a glass/calomel electrode system is determined with a pH meter or another voltage measuring device

Answer 22

potentiometric endpoint

Question 23

what elements that occur in organic and biological systems are conveniently determined by methods that have an acid-base titration as the final step

Answer 23

nonmetal elements
carbon
nitrogen
chlorine
bromine
fluorine

Question 24

occurs in a wide variety of substances of interest in the life sciences, in industry, and in agriculture. Examples include amino acids, proteins, synthetic drugs, fertilizers, explosives, soils, potable water supplies, and dyes

Answer 24

nitrogen

Question 25

most common method for determining organic nitrogen is the. sample is decomposed in hot conc sulfuric acid to convert the bound nitrogen to ammonium ion, which is then cooled, diluted, and made basic

Answer 25

Kjeldahl method

Question 26

a reagent containing copper(II) ions is used, and a violet colored complex is formed between the Cu21 ions and peptide bonds. The increase in the absorption of visible radiation is used to measure serum protein

Answer 26

Biuret method

Question 27

the serum sample is pretreated with an alkaline copper solution followed by a phenolic reagent. A color develops because of reduction of phosphotungstic acid and phosphomolybdic acid to molybdenum blue

Answer 27

lowry method

Question 28

the sample is mixed with powdered copper(II) oxide and ignited in a combustion tube to give carbon dioxide, water, nitrogen, and small amounts of nitrogen oxides

Answer 28

Dumas method

Question 29

are conveniently determined by conversion to ammonia with strong base followed by distillation. The ammonia is collected and titrated as in the Kjeldahl method.

Answer 29

ammonium salts

Question 30

50% Cu, 45% Al, and 5% Zn

Answer 30

devarda's alloy

Question 31

The method just described for ammonium salts can be extended to the determination of what inorganic substances

Answer 31

nitrates and nitrites

Question 32

The _________ of an acid or base is the mass of the compound that reacts with or contains 1 mole of protons

Answer 32

equivalent mass

Question 34

is the process by which an ester is hydrolyzed in alkaline solution to give an alcohol and a conjugate base.

Answer 34

saponification

Question 34

also called as the equivalent weight

Answer 34

equivalent mass

Question 35

generally have base dissociation constants on the order of 10^-5 and can be titrated directly with a solution of strong acid

Answer 35

amine groups

Question 35

have dissociation constants that range between 1024 and 1026, and thus, these compounds are readily titrated. An indicator that changes color in a basic range, such as phenolphthalein, is required.

Answer 35

carboxylic and sulfonic acids

Question 36

are commonly determined by saponification with a measured quantity of standard base

Answer 36

ester groups

Question 37

can be determined by esterification with various carboxylic acid anhydrides or chlorides. The two most common reagents are acetic anhydride and phthalic anhydride.

Answer 37

Hydroxyl groups in organic compounds

Question 38

can be determined with a solution of hydroxylamine hydrochloride.

Answer 38

carbonyl groups

Question 39

TRUE or FALSE The total salt content of a solution can be determined accurately by acid-base titration. The salt is converted to an equivalent amount of an acid or base by passing a solution containing the salt through a column packed with an ion-exchange resin

Answer 39

TRUE

Question 40

is an ion or a molecule that forms a covalent bond with a cation or a neutral metal atom by donating a pair of electrons, which are then shared by the two.

Answer 40

ligand

Question 41

A stock solution with a known hydrochloric acid concentration can also be prepared by diluting a quantity of the concentrated reagent with an equal volume of water followed by distillation. Under controlled conditions, the final quarter of the distillate, known as _________________HCl, has a constant and known composition.

Answer 41

constant-boiling

Question 42

can be prepared by heating purified sodium hydrogen carbonate between 270 and 300 degrees celsius for 1 hour

Answer 42

primary standard grade sodium carbonate

Question 43

TRUE or FALSE The second end point is always used for standardization because the change in pH is greater than that at the first

Answer 43

TRUE

Question 44

most common base used in titrtaion

Answer 44

sodium hydroxide potassium hydroxide barium hydroxide

Question 45

with atmospheric constituents contains only about 1.5 3 1025 mol CO2 /L, an amount that has a negligible effect on the strength of most standard bases. As an alternative to boiling to remove CO2 from supersaturated solutions of CO2, the excess gas can be removed by bubbling air through the water for several hours. This process is called

Answer 45

sparging

Question 46

sparging produced what

Answer 46

a solution that contains the equilibrium concentration of CO2

Question 47

is the process of removing a gas from a solution by bubbling an inert gas through the solution

Answer 47

sparging

Question 48

can be obtained in primary-standard purity and used for the standardization of bases has limited solubility in water, so it is usually dissolved in ethanol prior to dilution with water and titration

Answer 48

benzoic acid

Question 49

s an excellent primary standard with a high molar mass per mole of protons. It is also a strong acid that can be titrated using virtually any indicator with a transition range between pH 4 and 10.

Answer 49

potassium hydrogen iodate

Question 50

are particularly resistant to complete decomposition by sulfuric acid

Answer 50

pyridine pyridine derivatives some other heterocyclic compounds

Question 51

is frequently the most time-consuming aspect of a Kjeldahl determination.

Answer 51

decomposition step

Question 52

_______ in organic and biological materials is conveniently determined by burningthe sample in a stream of oxygen.

Answer 52

sulfur

Question 53

are conveniently determined by conversion to ammonia with strong base followed by distillation

Answer 53

ammonium salts

Question 54

These ions are first reduced to ammonium ion by reaction with an alloy of 50% Cu, 45% Al, and 5% Zn (Devarda’s alloy)

Answer 54

nitrates and nitrites

Question 55

60% Cu and 40% Mg is called

Answer 55

Arnd's alloy

Question 56

a method in which both components are titrated with a standard acid to the end point with an acid-range indicator, such as bromocresol green (the end point being established after the solution is boiled to remove carbon dioxide).

Answer 56

Winkler method

Question 57

provide convenient methods for the direct or indirect determination of several organic functional groups

Answer 57

neutralization titrations

Question 58

have dissociation constants that range between 10^4 and 10^6, with low solubility in water but readily soluble in ethanol

Answer 58

caboxylic acids

Question 59

are generally strong acids that easily dissolve in water

Answer 59

sulfonic acid

Question 60

generally have base dissociation constants on the order of 10^5 and can be titrated directly with a solution of strong acid.

Answer 60

aliphatic amines

Question 61

ommonly determined by saponification with a measured quantity of standard base, which is then titrated with standard acid

Answer 61

ester groups

Question 62

TRUE or FALSE The total salt content of a solution can be determined accurately by acid-base titration. The salt is converted to an equivalent amount of an acid or base by passing a solution containing the salt through a column packed with an ion-exchange resin

Answer 62

TRUE