Acids -Bases
TEACHER ANSWER KEY
June 02, 2011
'see explanation below'
1. Base your answer on the accompanying equation, which represents an organic compound
reacting with bromine.
What is the IUPAC name for the organic compound that reacts with Br2? [1]
See Reference Tables P and Q. The organic compound is an alkene that contains 3 carbon atoms.
Its IUPAC name is propene. [1 point]
'see explanation below'
2. Base your answer on the accompanying equation, which represents an organic compound
reacting with bromine.
What type of organic reaction is represented by this equation? [1]
The organic reaction is called addition. (Note that the terms halogenation and bromination are also
acceptable for credit.) [1 point]
'see explanation below'
3. Base your answer on the accompanying equation, which represents an organic compound
reacting with bromine.
What is the gram-formula mass of the product in this reaction? [1]
Complete the accompanying table for C3H6Br2 and add the numbers in the last column: [1 point]
'see explanation below'
4. Base your answer on the information below.
Many esters have distinctive odors, which lead to their widespread use as artificial flavorings and
fragrances. For example, methyl butanoate has an odor like pineapple and ethyl methanoate has an
odor like raspberry.
In the space provided or on a separate sheet of paper, draw a structural formula for the ester that has
an odor like pineapple. [1]
See Reference Tables P and R. The ester methyl butanoate is formed by the reaction of methanol (a
1-carbon alcohol) with butanoic acid (a 4-carbon organic acid). Three examples of acceptable
responses are shown in the accompanying image: [1 point]
'see explanation below'
5. Base your answer on the information below.
Many esters have distinctive odors, which lead to their widespread use as artificial flavorings and
fragrances. For example, methyl butanoate has an odor like pineapple and ethyl methanoate has an
odor like raspberry.
What is a chemical name for the alcohol that reacts with methanoic acid to produce the ester that
has an odor like raspberry? [1]
The ester ethyl methanoate is formed by the reaction of the alcohol ethanol with methanoic acid. [1
point]
'see explanation below'
6. Base your answer on the information below.
The incomplete equation shown represents an esterification reaction. The alcohol reactant is
represented by X.
On the structural formula on the answer sheet, or, if taken online, on a separate piece of paper,
circle the acid functional group, only. [1]
See Reference Table R. The functional group that is responsible for acidic properties is known as
the carboxyl group. It is shown in the accompanying diagram:
Note that either of these representations is acceptable for credit.
'see explanation below'
7. Base your answer on the information below.
The incomplete equation shown represents an esterification reaction. The alcohol reactant is
represented by X.
Write an IUPAC name for the reactant represented by its structural formula in this equation. [1]
The reactant whose structure is shown is an organic acid containing 2 carbon atoms. The name of
this compound is ethanoic (or acetic) acid.
'see explanation below'
8. Base your answer on the information below.
The incomplete equation shown represents an esterification reaction. The alcohol reactant is
represented by X.
In the space on the answer sheet, or, if taken online, on a separate piece of paper, draw the
structural formula for the alcohol represented by X. [1]
Esterification is the reaction between an acid and an alcohol. Therefore, compound X must be a 3carbon alcohol. Two acceptable versions of its structure are shown in the accompanying diagram:
'see explanation below'
9. Base your answer on the information below. The equation shown (see image) represents the
reaction between butanoic acid and an unidentified reactant, X.
Identify the type of organic reaction represented by the equation. [1]
Use Reference Table R to identify the organic product, which is an ester. The reaction is known as
esterification (or dehydration synthesis). [1 point]
'see explanation below'
10. Base your answer on the information below. The equation shown (see image) represents the
reaction between butanoic acid and an unidentified reactant, X.
In the space on the answer sheet or on a separate piece of paper, draw a structural formula for the
unidentified reactant, X, in the equation. [1]
In an esterification reaction, an organic acid (in this case, butanoic acid) reacts with an alcohol to
produce an ester and water. Since butanoic acid has four carbon atoms and the ester has six carbon
atoms, we can deduce that alcohol X has two carbon atoms. Its structural formula is:
'see explanation below'
11. Base your answer on the information below.
Gasoline is a mixture composed primarily of hydrocarbons such as isooctane, which is also known
as 2,2,4-trimethylpentane.
Gasoline is assigned a number called an octane rating. Gasoline with an octane rating of 87
performs the same as a mixture that consists of 87% isooctane and 13% heptane.
An alternative fuel, E-85, can be used in some automobiles. This fuel is a mixture of 85% ethanol
and 15% gasoline.
In the space provided or on a separate piece of paper, draw a structural formula for a molecule of
2,2,4-trimethylpentane. [1]
The compound 2,2,4-trimethylpentane has three methyl groups (CH3) bonded to carbons 2, 2, and 4
of pentane. Two acceptable structures are shown in the accompanying diagram: [1 point]
'see explanation below'
12. Base your answer on the information below.
Gasoline is a mixture composed primarily of hydrocarbons such as isooctane, which is also known
as 2,2,4-trimethylpentane.
Gasoline is assigned a number called an octane rating. Gasoline with an octane rating of 87
performs the same as a mixture that consists of 87% isooctane and 13% heptane.
An alternative fuel, E-85, can be used in some automobiles. This fuel is a mixture of 85% ethanol
and 15% gasoline.
Identify the functional group in a molecule of ethanol in the alternative fuel E-85. [1]
Ethanol is an alcohol and contains the –OH (hydroxyl) group. [1 point]
'see explanation below'
13. What color is bromcresol green after it is added to a sample of NaOH(aq)? [1]
See Reference Tables L and M. NaOH(aq) is a strongly basic solution. The color of bromcresol
green changes to blue at pH values greater than or equal to 5.4. Therefore, the color of the solution
will be blue.
'see explanation below'
14. Base your answer on the information below.
In a laboratory activity, 0.500 mole of NaOH(s) is completely dissolved in distilled water to form
400. milliliters of NaOH(aq). This solution is then used to titrate a solution of HNO3(aq).
Identify the negative ion produced when the NaOH(s) is dissolved in distilled water. [1]
When sodium hydroxide (NaOH) is dissolved in water, positive Na+(aq) ions and negative OH–(aq)
ions are produced.
'see explanation below'
15. Base your answer on the information below.
In a laboratory activity, 0.500 mole of NaOH(s) is completely dissolved in distilled water to form
400. milliliters of NaOH(aq). This solution is then used to titrate a solution of HNO3(aq).
In the space on the answer sheet, or, if taken online, on a separate piece of paper, calculate the
molarity of the NaOH(aq). Your response must include both a correct numerical setup and the
calculated result. [2]
Use the concentration (molarity) equation found on Reference Table T (see diagram):
One point is awarded for a correct numerical setup, and one point is allowed for an answer that is
consistent with the numerical setup.
'see explanation below'
16. Base your answer on the information below.
In a laboratory activity, 0.500 mole of NaOH(s) is completely dissolved in distilled water to form
400. milliliters of NaOH(aq). This solution is then used to titrate a solution of HNO3(aq).
In the space on the answer sheet, or, if taken online, on a separate piece of paper, complete the
equation representing this titration reaction by writing the formulas of the products. [1]
The equation for the titration is shown below:
NaOH(aq) + HNO3(aq) → NaNO3(aq) + H2O(l )
'see explanation below'
17. Base your answer on the information below.
When a person perspires (sweats), the body loses many sodium ions and potassium ions. The
evaporation of sweat cools the skin.
After a strenuous workout, people often quench their thirst with sports drinks that contain NaCl and
KCl. A single 250.-gram serving of one sports drink contains 0.055 gram of sodium ions.
State why the salts in sports drinks are classified as electrolytes. [1]
When salts dissolve in water, the dissolved ions become mobile and the solution can conduct an
electric current. [1 point]
'see explanation below'
18. Base your answer on the information below.
A student used blue litmus paper and phenolphthalein paper as indicators to test the pH of distilled
water and five aqueous household solutions. Then the student used a pH meter to measure the pH
of the distilled water and each solution. The results of the student's work are recorded in the
accompanying table.
Identify the liquid tested that has the lowest hydronium ion concentration. [1]
The lowest hydronium ion concentration will be found in the liquid with the highest pH value,
household ammonia. [1 point]
'see explanation below'
19. Base your answer on the information below.
A student used blue litmus paper and phenolphthalein paper as indicators to test the pH of distilled
water and five aqueous household solutions. Then the student used a pH meter to measure the pH
of the distilled water and each solution. The results of the student's work are recorded in the
accompanying table.
Explain, in terms of the pH range for color change on Reference Table M, why litmus is not
appropriate to differentiate the acidity levels of tomato juice and vinegar. [1]
According to Reference Table M, litmus begins to change from red to blue at a pH value of 5.5.
Since tomato juice and vinegar have pH values below 5.5, both of these liquids will turn litmus red.
Therefore, litmus cannot be used to distinguish between the liquids. [1 point]
'see explanation below'
20. Base your answer on the information below.
A student used blue litmus paper and phenolphthalein paper as indicators to test the pH of distilled
water and five aqueous household solutions. Then the student used a pH meter to measure the pH
of the distilled water and each solution. The results of the student's work are recorded in the
accompanying table.
Based on the measured pH values, identify the liquid tested that is 10 times more acidic than
vinegar. [1]
Each 1 pH unit represents a tenfold change in the hydronium ion concentration. A decrease of 1 pH
unit represents a tenfold increase in the hydronium ion concentration. Therefore, in order for a
liquid to be 10 times more acidic than vinegar, it must have a pH of 2.3, such as lemon juice. [1
point]
'see explanation below'
21. Base your answer on the information below.
In one trial of an investigation, 50.0 milliliters of HCl(aq) of an unknown concentration is titrated
with 0.10 M NaOH(aq). During the titration, the total volume of NaOH(aq) added and the
corresponding pH value of the reaction mixture are measured and recorded in the accompanying
table.
Write a balanced equation that represents this neutralization reaction. [1]
In a neutralization reaction, an acid and a base combine to produce a salt and water, as shown
below:
NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l)
[1 point]
'see explanation below'
22. Base your answer on the information below.
In one trial of an investigation, 50.0 milliliters of HCl(aq) of an unknown concentration is titrated
with 0.10 M NaOH(aq). During the titration, the total volume of NaOH(aq) added and the
corresponding pH value of the reaction mixture are measured and recorded in the accompanying
table.
In another trial, 40.0 milliliters of HCl(aq) is completely neutralized by 20.0 milliliters of this 0.10
M NaOH(aq). Calculate the molarity of the titrated acid in this trial. Your response must include
both a numerical setup and the calculated result. [2]
Use the titration equation given on Reference Table T: (see image)
One point is given for a correct numerical setup, and one point is awarded for a response consistent
with the numerical setup. [2 points]
4
23. Which notation of a radioisotope is correctly paired with the notation of its emission particle?
4 See Reference Tables N and O. 3H is a (beta)- emitter, that is, an electron ( 0-1e) emitter.
Wrong Choices Explained:
(1) 37Ca is a positron ( 0+1e) emitter.
(2) 235U is an alpha particle (42 He) emitter.
(3) 16N is an electron ( 0-1e) emitter.
4
24. Atoms of one element are converted to atoms of another element through
1. fermentation
3. polymerization
2. oxidation
4. transmutation
4 In a transmutation reaction, one element is converted into another.
4
25. Which notation of a radioisotope is correctly paired with the notation of its emission particle?
4 See Reference Tables N and O. 3H is a (beta)- emitter, that is, an electron ( 0-1e) emitter.
Wrong Choices Explained:
(1) 37Ca is a positron ( 0+1e) emitter.
(2) 235U is an alpha particle (42 He) emitter.
(3) 16N is an electron ( 0-1e) emitter.
4
26. Atoms of one element are converted to atoms of another element through
1. fermentation
3. polymerization
2. oxidation
4. transmutation
4 In a transmutation reaction, one element is converted into another.
1
27. A molecule of butane and a molecule of 2-butene both have the same total number of
1. carbon atoms
3. single bonds
2. hydrogen atoms
4. double bonds
1 See Reference Table P. The organic prefix but- stands for 4 carbon atoms. Therefore, molecules
of butane and 2-butene have the same number of carbon atoms.
2
28. Which general formula represents the homologous series of hydrocarbons that includes the
compound l-heptyne?
1. Cn H2n–6
3. Cn H2n
2. Cn H2n -2
4. Cn H2n+2
2 See Reference Table Q. The suffix -yne stands for the alkyne series of hydrocarbons, which has
the general formula Cn H2n -2.
2
29. Which two compounds are isomers of each other?
1. CH3CH2COOH and CH3COOCH2CH3
3. CH3CHBrCH3 and CH2BrCHBrCH3
2. CH3CH2CHO and CH3COCH3
4. CH3CHOHCH3 and CH3CHOHCH2OH
2 See Reference Table R. Isomers are compounds that have the same molecular formula but
different structural formulas. Of the choices given, only choice (2), CH3CH2CHO and CH3COCH3,
meets this requirement. Although both compounds have the same molecular formula (C3H6O), the
first compound is an aldehyde and the second is a ketone.
2
30. Which formula represents an unsaturated hydrocarbon?
2 An unsaturated hydrocarbon is a compound that contains only carbon and hydrogen atoms and
has at least one double or triple carbon-to-carbon bond. Of the choices given, only the structure
shown in choice (2) meets both requirements.
2
31. Hydrocarbons are compounds that contain
1. carbon, only
3. carbon, hydrogen, and oxygen, only
2. carbon and hydrogen, only
4. carbon, hydrogen, oxygen, and nitrogen, only
2 By definition, hydrocarbons are organic compounds that contain carbon and hydrogen, only.
3
32. The reaction that joins thousands of small, identical molecules to form one very long molecule
is called
1. esterification
3. polymerization
2. fermentation
4. substitution
3 In polymerization, individual molecules called monomers join chemically (by addition or
condensation) to form large, complex molecules known as polymers.
Wrong Choices Explained:
(1) In esterification, an alcohol and an organic acid react to produce water and the organic product,
which is classified as an ester.
(2) In fermentation, a sugar is converted by yeast enzymes into an alcohol and carbon dioxide.
(4) In substitution, an atom such as chlorine replaces an atom such as hydrogen (which is bonded to
a carbon atom in an organic compound).
2
33. What is the IUPAC name of the organic compound that has the formula shown below?
1. 1,1-dimethylbutane
3. hexane
2. 2-methylpentane
4. 4-methylpentane
2 The parent name of this molecule is pentane since the longest unbroken chain consists of 5
carbon atoms. The number of the carbon on which the methyl group (CH3–) is placed is 2 because
the parent chain is numbered in order to produce the smallest number, in this case, from right to
left.
1
34. Which compound is a member of the same homologous series as C3H8?
1. CH4
3. C5H8
2. C4H8
4. C5H10
1 Use Reference Table Q. C3H8 belongs to the alkane series of hydrocarbons, whose general
formula is CnH2n+2. Of the choices given, only choice (1), CH4, has this same general formula.
Wrong Choices Explained:
(2), (4) The general formula of these compounds is CnH2n. (3) The general formula of this
compound is CnH2n-2.
3
35. A straight-chain hydrocarbon that has only one double bond in each molecule has the general
formula
1. CnH2n-6
3. CnH2n
2. CnH2n-2
4. CnH2n+2
3 See Reference Table Q. The alkene family of hydrocarbons consists of straight-chain molecules
with one double bond. The general formula for this series is CnH2n.
Wrong Choices Explained:
(1) The general formula CnH2n-6 represents the benzene family of hydrocarbons, which are ring
compounds.
(2) The general formula CnH2n-2 represents the alkyne family of hydrocarbons.
(4) The general formula CnH2n+2 represents the alkane family of hydrocarbons.
4
36. Which reaction results in the production of soap?
1. esterification
3. polymerization
2. fermentation
4. saponification
4 Saponification is the reaction of a long-chain organic acid with sodium or potassium hydroxide.
The resultant ionic compound is known as soap.
1
37. Ethanol and dimethyl ether have different chemical and physical properties because they have
different
1. functional groups
3. numbers of covalent bonds
2. molecular masses
4. percent compositions by mass
1 Ethanol (CH3CH2OH) is an alcohol, while dimethyl ether (CH3OCH3) is an ether. Even though
they both have the same molecular formula (C2H6O), they have different functional groups and
different molecular structures. Therefore, these two compounds have different chemical and
physical properties.
1
38. Which formula represents an unsaturated hydrocarbon?
1 An unsaturated hydrocarbon contains only carbon and hydrogen atoms with at least one double or
triple bond between two adjacent carbon atoms. Of the choices given, only the structural formula
given in choice (1) meets both criteria.
1
39. Which element is present in all organic compounds?
1. carbon
3. nitrogen
2. hydrogen
4. oxygen
1 Organic chemistry is the study of carbon compounds.
4
40. Which formula represents an unsaturated hydrocarbon?
1. C5H12
3. C7H16
2. C6H14
4. C8H14
4 Simple unsaturated hydrocarbons contain double or triple bonds. Their general formulas are
CnH2n and CnH2n–2, respectively. The general formula of choice (4), C8H14, is CnH2n–2.
Wrong Choices Explained:
(1), (2), (3),The general formula for each of these hydrocarbons is CnH2n+2. They are all saturated
hydrocarbons.
4
41. The reaction between an organic acid and an alcohol produces
1. an aldehyde
3. an ether
2. a ketone
4. an ester
4 See Reference Table R. Esterification is the reaction between an acid and an alcohol. During the
reaction, a molecule of water is removed from the reactants and an organic compound known as an
ester is produced.
2
42. Which formula represents a molecule of a saturated hydrocarbon?
1. C2H2
3. C5H8
2. C4H10
4. C6H6
1
43. Molecules of 2-methyl butane and 2,2-dimethyl propane have different
1. structural formulas
3. numbers of carbon atoms
2. molecular formulas
4. numbers of covalent bonds
4
44. The molecule shown belongs to which class of compounds?
1. alcohol
3. aldehyde
2. ester
4. amino acid
1
45. Given the incomplete reaction: . . . (see image)
Which compound is represented by x?
3
46. Which substance is an Arrhenius acid?
1. NH3
3. HC2H3O2
2. KOH
4. CH3OH
1
47. Which of the following pH values indicates the highest concentration of hydronium ions in a
solution?
1. pH = 1
3. pH = 3
2. pH = 2
4. pH = 4
1
48. Which substance yields hydroxide ion as the only negative ion in aqueous solution?
1. Mg(OH)2
3. MgCl2
2. C2H4(OH)2
4. CH3Cl
4
49. What is the molarity of an HCl solution if 20. milliliters of this acid is needed to neutralize 10.
milliliters of a 0.50 M NaOH solution?
1. 1.0 M
3. 0.50 M
2. 0.75 M
4. 0.25 M
3
50. Which substance is an Arrhenius acid?
1. NH3
3. HC2H3O2
2. KOH
4. CH3OH
1
51. Which of the following pH values indicates the highest concentration of hydronium ions in a
solution?
1. pH = 1
3. pH = 3
2. pH = 2
4. pH = 4
1
52. Which substance yields hydroxide ion as the only negative ion in aqueous solution?
1. Mg(OH)2
3. MgCl2
2. C2H4(OH)2
4. CH3Cl
4
53. What is the molarity of an HCl solution if 20. milliliters of this acid is needed to neutralize 10.
milliliters of a 0.50 M NaOH solution?
1. 1.0 M
3. 0.50 M
2. 0.75 M
4. 0.25 M
4
54. Which aqueous solution is the best conductor of an electrical current?
1. 0.01 M CH3OH
3. 0.1 M CH3OH
2. 0.01 M KOH
4. 0.1 M KOH
4 An electrolyte is a substance that dissolves in water and produces a solution that conducts
electricity because ions are released in solution. KOH is an ionic compound that is a strong
electrolyte. Choice (4), 0.1 M KOH, will be the best conductor because the concentrations of K+
and OH¿- ions are greatest. Wrong Choices Explained: (1), (3) CH3OH is a molecular substance.
When dissolved in water, no ions are produced in solution.
3
55. A hydrogen ion, H+, in aqueous solution may also be written as
1. H2O
3. H3O+
2. H2O2
4. OH-
3 Another way of writing H+(aq) is to show it combined with a molecule of H2O, that is, as
H3O+(aq).
3
56. One acid-base theory states that an acid is
1. an electron donor
3. an H+ donor
2. a neutron donor
4. an OH- donor
3 The Brönsted-Lowry theory of acids and bases states that an acid is a proton (H+) donor.
1
57. Note: This question may require the use of the Reference Tables for Physical Setting/Chemistry.
How are HNO3(aq) and CH3COOH(aq) similar?
1. They are Arrhenius acids and they turn blue
litmus red.
3. They are Arrhenius bases and they turn blue
litmus red.
2. They are Arrhenius acids and they turn red
litmus blue.
4. They are Arrhenius bases and they turn red
litmus blue.
1 See Reference Tables K and M. HNO3 and CH3COOH are classified as Arrhenius acids because
both can liberate H+ ions in aqueous solution. The color of litmus in an acidic solution is red.
3
58. A substance is classified as an electrolyte because
1. it has a high melting point
3. its aqueous solution conducts an electric
current
2. it contains covalent bonds
4. its aqueous solution has a pH value of 7
3 By definition, an electrolyte is a substance whose aqueous solution conducts electricity.
1
59. The compound NaOH(s) dissolves in water to yield
1. hydroxide ions as the only negative ions
3. hydronium ions as the only negative ions
2. hydroxide ions as the only positive ions
4. hydronium ions as the only positive ions
1 An Arrhenius base is defined as a substance that produces hydroxide ion (OH-) as the only
negative ion in solution. See Reference Table L. The compound NaOH is an Arrhenius base.
3
60. Which equation represents a neutralization reaction?
1. 4Fe(s) + 3O2(g) --> 2Fe2O3(s)
3. HNO3(aq) + KOH(aq) --> KNO3(aq) + H2O(l
)
2. 2H2(g) + O2(g) --> 2H2O(l )
4. AgNO3(aq) + KCl(aq) --> KNO3(aq) +
AgCl(s)
3 A neutralization reaction is one in which an Arrhenius acid (such as HNO3) and an Arrhenius
base (such as KOH) react to produce a salt (such as KNO3) and H2O.
Wrong Choices Explained:
(1), (2) These reactions are classified as both synthesis reactions and oxidation-reduction reactions.
(4) This reaction is classified as a double-replacement reaction.
4
61. Solution A has a pH of 3 and solution Z has a pH of 6. How many times greater is the
hydronium ion concentration in solution A than the hydronium ion concentration in solution Z?
1. 100
3. 3
2. 2
4. 1000
4 A decrease of 1 pH unit represents a tenfold increase in the hydronium ion concentration. Since
the pH of A is 3 pH units lower than the pH of Z, the hydronium concentration of A is 1000 times
greater than the hydronium concentration of Z.
1
62. Which indicator is blue in a solution that has a pH of 5.6?
1. bromcresol green
3. methyl orange
2. bromthymol blue
4. thymol blue
1 Examine the pH ranges given on Reference Table M. Only choice (3), bromcresol green, is blue
at a pH of 5.6.
Wrong Choices Explained:
(2) Bromthymol blue is yellow at a pH of 5.6.
(3) Methyl orange is yellow at a pH of 5.6.
(4) Thymol blue is yellow at a pH of 5.6.
1
63. The Arrhenius theory explains the behavior of
1. acids and bases
3. isomers and isotopes
2. alcohols and amines
4. metals and nonmetals
1 An Arrhenius acid is defined as a substance that produces hydronium ions (H+ or H3O+) as the
only positive ions in aqueous solution. An Arrhenius base is defined as a substance that produces
hydroxide ions (OH-) as the only negative ions in aqueous solution.
4
64. In which laboratory process could a student use 0.10 M NaOH(aq) to determine the
concentration of an aqueous solution of HBr?
1. chromatography
3. evaporation of the solvent
2. decomposition of the solute
4. titration
4 Titration is the laboratory process in which a measured volume of a standard base (in this case
0.10M NaOH(aq)) is used to neutralize a known volume of an acid (such as HBr). This information
can be used to calculate the concentration of the acid. See the titration formula given on Reference
Table T.
3
65. Given the balanced equation representing a reaction:
NH3(g) + H2O(l ) → NH4+(aq) + OH-(aq)
According to one acid-base theory, the NH3(g) molecules act as
1. an acid because they accept H+ ions
3. a base because they accept H+ ions
2. an acid because they donate H+ ions
4. a base because they donate H+ ions
3 In the equation NH3(g) + H2O(l ) → NH4 +(aq) + OH–(aq), an NH3 molecule accepts an H+ ion
and forms NH4 +. In the Bronsted-Lowry acid-base model, a base is an H+ acceptor.
2
66. What volume of 0.120 M HNO3(aq) is needed to completely neutralize 150.0 milliliters of
0.100 M NaOH(aq)?
1. 62.5 mL
3. 180. mL
2. 125 mL
4. 360. mL
2 Use the titration equation on Reference Table T:
2
67. Which substance is always a product when an Arrhenius acid in an aqueous solution reacts with
an Arrhenius base in an aqueous solution?
1. HBr
3. KBr
2. H2O
4. KOH
2 In a neutralization reaction, the hydroxide ions of an Arrhenius base react with the hydronium
ions of an Arrhenius acid to produce water. The two remaining (spectator) ions form a salt.
3
68. Which substance is an electrolyte?
1. CCl4
3. HCl
2. C2H6
4. H2O
3 An electrolyte is a substance that is ionic or can produce a large number of ions when dissolved
in water. The presence of these dissolved ions enables the solution to conduct electricity. Of the
choices given, only choice (3), HCl, is an electrolyte because it ionizes nearly 100% when
dissolved in water.
Wrong Choices Explained:
(1), (2) CCl4 and C2H6 do not ionize in water.
(4) H2O does ionize but to a negligibly small extent, resulting in very poor conductivity.
2
69. One acid-base theory defines a base as an
1. H+ donor
3. H donor
2. H+ acceptor
4. H acceptor
2 One alternative acid-base theory is based on H+ transfer. A base is defined as an H+ acceptor.
2
70. A student completes a titration by adding 12.0 milliliters of NaOH(aq) of unknown
concentration to 16.0 milliliters of 0.15 M HCl(aq). What is the molar concentration of the
NaOH(aq)?
1. 0.11 M
3. 1.1 M
2. 0.20 M
4. 5.0 M
2 Use the titration equation on Reference Table T: (see image)
4
71. Based on the results of testing colorless solutions with indicators, which solution is most
acidic?
1. a solution in which bromthymol blue is blue
3. a solution in which phenolphthalein is pink
2. a solution in which bromcresol green is blue
4. a solution in which methyl orange is red
4 A solution is acidic if its pH is less than 7.0. As the pH decreases, the acidity of the solution
increases. Use Reference Table M. Methyl orange is red at a pH of 3.2 or less.
Wrong Choice Explained:
(2) In a solution in which bromcresol green is blue in color, the pH can be as low as 5.4. This value
is less acidic than a solution whose pH is 3.2.
2
72. Which compound is an Arrhenius acid?
1. CaO
3. K2O
2. HCl
4. NH3
2 An Arrhenius acid is one that releases H+ ion in aqueous solution. Use Reference Table K. HCl is
one of the more common Arrhenius acids.
2
73. According to one acid-base theory, water acts as an acid when an H2O molecule
1. accepts an H+
3. accepts an H-
2. donates an H+
4. donates an H-
2 The Brönsted-Lowry acid-base model defines an acid as a molecule or ion that donates an H+ ion
and a base as one that accepts an H+ ion.
3
74. A solution with a pH of 2.0 has a hydronium ion concentration ten times greater than a solution
with a pH of
1. 1.0
3. 3.0
2. 0.20
4. 20.
3 For each change of 1 pH unit, the hydronium ion concentration of a solution changes tenfold. The
hydronium ion concentration of a solution with a pH of 3.0 is ten times less than the hydronium ion
concentration of a solution with a pH of 2.0.