2001 ap chemistry questions - college board€¦ · · 2017-06-30ap chemistry 2001 free-response...

AP Chemistry 2001 Free-Response Questions

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GO ON TO THE NEXT PAGE.2

INFORMATION IN THE TABLE BELOW AND IN THE TABLES ON PAGES 3-5 MAY BE USEFUL IN ANSWERINGTHE QUESTIONS IN THIS SECTION OF THE EXAMINATION.

DO

NO

T D

ET

AC

H F

RO

M B

OO

K.

PE

RIO

DIC

TA

BL

E O

F T

HE

EL

EM

EN

TS

1 3 11 19 37

85.4

755

132.

9187 (223

)

4 12 20 38

87.6

256

137.

3388

226.

02

21 39

88.9

157

138.

9189

227.

03

22 40

91.2

272

178.

49

23 41

92.9

173

180.

95

24 42

95.9

474

183.

85

25 43 (98) 75

186.

21

26 44

101.

176

190.

2

27 45

102.

9177

192.

2

28 46

106.

4278

195.

08

29 47

107.

8779

196.

97

30 48

112.

4180

200.

59

5 13 31 49

114.

8281

204.

38

6 14 32 50

118.

7182

207.

2

7 15 33 51

121.

7583

208.

98

8 16 34 52

127.

6084 (209

)

9 17 35 53

126.

9185 (210

)

10 18 36 54

131.

2986 (222

)

H Li

Na K Rb

Cs

Fr

Be

Mg

Ca

Sr Ba

Ra

Sc Y *La

Ac

Ti

Zr

Hf

V Nb

Ta

Cr

Mo

W

Mn

Tc

Re

Fe

Ru

Os

Co

Rh Ir

Ni

Pd Pt

Cu

Ag

Au

Zn

Cd

Hg

110

(269

)

111

(272

)

112

(277

)

§§

§

B Al

Ga

In Tl

C Si Ge

Sn Pb

N P As

Sb Bi

O S Se Te

Po

F Cl

Br I At

Ne

Ar

Kr

Xe

Rn

He

104

(261

)

105

(262

)

106

(263

)

107

(262

)

108

(265

)

109

(266

)

Rf

Db

SgB

hH

sM

t

2

1.00

79

6.94

1

22.9

9

39.1

0

9.01

2

24.3

0

40.0

844

.96

47.9

050

.94

52.0

054

.938

55.8

558

.93

58.6

963

.55

65.3

9

10.8

11

26.9

8

69.7

2

12.0

11

28.0

9

72.5

9

14.0

07

30.9

74

74.9

2

16.0

0

32.0

6

78.9

6

19.0

0

35.4

53

79.9

0

20.1

79

39.9

48

83.8

0

4.00

26

5859

6061

6263

6465

6667

6869

7071

9091

9293

9495

9697

9899

100

101

102

Ce

Pr

Nd

Pm

SmE

uG

dT

bD

yH

oE

rT

mY

bL

u

Th

Pa

UN

pP

uA

mC

mB

kC

fE

sF

mM

dN

oL

r10

314

0.12

140.

9114

4.24

(145

)15

0.4

151.

9715

7.25

158.

9316

2.50

164.

9316

7.26

168.

9317

3.04

174.

97

232.

0423

1.04

238.

0323

7.05

(244

)(2

43)

(247

)(2

47)

(251

)(2

52)

(257

)(2

58)

(259

)(2

60)

*Lan

than

ide

Ser

ies

†Act

inid

e S

erie

s

†§N

ot y

et n

amed


STANDARD REDUCTION POTENTIALS IN AQUEOUS SOLUTION AT 25°C

Half-reaction E °( )V

Li

Cs

Li

Cs

K K

Rb Rb

Ba Ba

Sr 2 Sr

Ca 2 Ca

Na Na

Mg 2 Mg(

Be 2 Be

Al 3 Al

Mn 2 Mn

+ -

+ -

+ -

+ -

+ -

+ -

+ -

+ -

+ -

+ -

+ -

+ -

� � ��

� � ��

� � ��

� � ��

e

e

e

e

e

e

e

e

e

e

e

e

s

s

s

s

s

s

s

s

s

s

s

s

( ) .

( ) .

( ) .

( ) .

( ) .

( ) .

( ) .

( ) .

) .

( ) .

( ) .

( )

3 05

2 92

2 92

2 92

2 2 90

2 89

2 87

2 71

2 37

1 70

1 66

2

2

2

2

2

3

2 118

0 76

0 74

0

0

0

0 34

0 28

0 25

0 14

0 13

2 0 00

2

2

3

2

3 2

2

2

2

2

2

.

( ) .

( ) .

( ) .44

.41

( ) .40

( ) .

) .

( ) .

( ) .

( ) .

( ) .

( )

Zn 2 Zn

Cr 3 Cr

Fe 2 Fe

Cr Cr

Cd 2 Cd

Tl Tl

Co 2 Co(

Ni 2 Ni

Sn 2 Sn

Pb 2 Pb

H 2 H

S H

2 +

+ -

+ -

+ -

+ - +

+ -

+ -

+ -

+ -

-

+ -

+ -

� � ��

� � ��

�

e

e

e

e

e

e

e

e

e

e

e

s

s

s

s

s

s

s

s

s

g

s + -

+ - +

+ - +

+ -

+ -

- -

+ - +

+ -

+ -

+ -

+ - +

- -

� ��

� ��

� ��

� ��

�

2 H S 0.14

Sn 2 Sn

Cu Cu

Cu 2 Cu

Cu Cu

I 2 I

Fe Fe

Hg 2 Hg(

Ag Ag(

Hg 2 Hg(

Hg 2 Hg

Br 2 Br

O

e

e

e

e

e

e

e

e

e

e

e

e

g

s

s

s

l

s

l

l

g

24 2

2

2

23 2

22

2

22

2

2

2

0 15

0 15

0 34

0 52

2 0 53

0 77

2 0 79

0 80

0 85

2 0 92

2 1 07

4

( )

.

.

( ) .

( ) .

( ) .

.

) .

) .

) .

.

( ) .

( ) H 4 H O(

Cl Cl

Au Au

Co Co

F 2 F

+ -

- -

+ -

+ - +

- -

� ��

� ��

e

e

e

e

e

l

g

s

g

2 1 23

2 2 136

3 1 50

182

2 2 87

2

23

3 2

2

) .

( ) .

( ) .

.

( ) .


ADVANCED PLACEMENT CHEMISTRY EQUATIONS AND CONSTANTS

E

v

p

n

m

=======

energy

frequency

wavelength

momentum

velocity

principal quantum number

mass

l

u

Speed of light, m s

Planck’s constant, J s

Boltzmann’s constant, J K

Avogadro’s number molecules mol

Electron charge, coulomb

1 electron volt per atom kJ mo

l

c

h

k

e

= ×

= ×

= ×

= ×

= − ×

=

−

−

− −

−

−

−

3 0 10

6 63 10

1 38 10

6 022 10

1 602 10

96 5

8 1

34

23 1

23 1

19

1

.

.

.

.

.

.

ATOMIC STRUCTURE

DE v

v

=h

m

m

==

=

= − × −

h

c

p

En

n

l

lu

u

2 178 10 18

2.

joule

EQUILIBRIUM

K

K

K

a

b

b

=

=

=

+ −

− +

− + −

+ −

−

+

= ×= ×

= − = −= +

= +

= +

= − = −

=

= −

[ ] [ ][ ]

[ ] [ ][ ]

[ ] [ ] .

log [ ], log [ ]

log[ ][ ]

log[ ]

[ ]log , log

( ) ,

H AHA

OH HBB

OH H @ 25 C

pH H pOH OH

pH pOH

pH pAHA

pOH pHB

Bp p

where moles product gas moles reactant gas

K

K

K

K

K K K K

K K RT

n

w

a

a

b

a a b b

p cn

1 0 10

14

14 �

D

D

THERMOCHEMISTRY

D

D D D

D D D

D D D

D D D

D

D

D

S S S

H H H

G G G

G H T S

RT K RT K

n E

G G RT Q G RT Q

q mc T

CH

T

f f

f f

p

� � �

� � �

� � �

� � �

� �

o

= −

−

= −

−

= − = −

= −

= + = +=

=

∑ ∑∑ ∑∑ ∑

=

=

products reactants

products reactants

products reactants

ln . log

ln . log

2 303

2 303

�

Equilibrium Constants

(weak acid)

(weak base)

(water)

(gas pressure)

(molar concentrations)

K

K

K

K

K

a

b

w

p

c

S

H

G

E

T

n

m

q

c

Cp

�

�

�

�

=

=

=

=======

=

standard entropy

standard enthalpy

standard free energy

standard reduction potential

temperature

moles

mass

heat

specific heat capacity

molar heat capacity at constant pressure

faraday coulombs1 96 500� ,


GASES, LIQUIDS, AND SOLUTIONS

PV nRT

Pn a

VV nb nRT

X X

P P P P

nm

PVT

P VT

DmV

ukTm

RT

KE m

KE RT

rr

M

T iK

T iK

nRTV

i

P PA total A A

total A B C

rms

f f

b b

�

� � �

�

� � � �

�

� �

�

� �

�

�

��

� �

�

��

��

� �

�

�

2

2

2

273

3 3

1232

1 1

1

2 2

2

1

2

2

1

( )

. . .

, wheremoles A

total moles

K C

per molecule

per mole

molarity, moles solute per liter solution

molality moles solute per kilogram solvent

molality

molality

M

M

MM

o

u

D

D

p

OXIDATION-REDUCTION; ELECTROCHEMISTRY

Q a b c d

Iq

t

E ERT

nQ E

nQ C

KnE

c d

= + → +

=

= − = −

=

[ ] [ ]

[ ] [ ]

ln.

log @

log.

,C D

A Bwhere A B C D

cell cell cell

a b

� � �

�

�

0 059225

0 0592

P

V

T

n

D

m

=======

pressure

volume

temperature

number of moles

density

mass

velocityu

u

KE

r

i

K

K

Q

I

q

t

E

K

rms

f

b

=======

=====

==

root-mean-square speed

kinetic energy

rate of effusion

molar mass

osmotic pressure

van’t Hoff factor

molal freezing-point depression constant

molal boiling-point elevation constant

reaction quotient

current (amperes)

charge (coulombs)

time (seconds)

standard reduction potential

equilibrium constant

M

p

o

Gas constant, J mol K

L atm mol K

volt coulomb mol K

Boltzmann’s constant, J K

for H O K kg mol

for H O K kg mol

STP C and atm

Faraday’s constant, coulombs per mole

of electrons

R

k

K

K

f

b

=

=

=

= ×

=

=

=

− −

− −

− −

− −

−

−

=

8 31

0 0821

8 31

1 38 10

1 86

0 512

0 000 1 000

96 500

1 1

1 1

1 1

23 1

21

21

.

.

.

.

.

.

. .

,

�

�

2001 AP® CHEMISTRY FREE-RESPONSE QUESTIONS

Copyright © 2001 by College Entrance Examination Board. All rights reserved.Advanced Placement Program and AP are registered trademarks of the College Entrance Examination Board.


CHEMISTRYSection II

(Total time—90 minutes)

Part ATime—40 minutes

YOU MAY USE YOUR CALCULATOR FOR PART A.

CLEARLY SHOW THE METHOD USED AND THE STEPS INVOLVED IN ARRIVING AT YOUR ANSWERS.It is to your advantage to do this, since you may obtain partial credit if you do and you will receive little or no credit ifyou do not. Attention should be paid to significant figures.

Be sure to write all your answers to the questions on the lined pages following each question in the booklet with thepink cover. Do NOT write your answers on the green insert.

Answer Question 1 below. The Section II score weighting for this question is 20 percent.

1. Answer the following questions relating to the solubility of the chlorides of silver and lead.

(a) At 10°C, 8.9 � 10−5 g of AgCl(s) will dissolve in 100. mL of water.

(i) Write the equation for the dissociation of AgCl(s) in water.

(ii) Calculate the solubility, in mol L-1, of AgCl(s) in water at 10°C.

(iii) Calculate the value of the solubility-product constant, Ksp, for AgCl(s) at 10°C.

(b) At 25°C, the value of Ksp for PbCl2(s) is 1.6 � 10−5 and the value of Ksp for AgCl(s) is 1.8 � 10−10.

(i) If 60.0 mL of 0.0400 M NaCl(aq) is added to 60.0 mL of 0.0300 M Pb(NO3)2(aq), will a precipitateform? Assume that volumes are additive. Show calculations to support your answer.

(ii) Calculate the equilibrium value of [Pb2+(aq)] in 1.00 L of saturated PbCl2 solution to which 0.250mole of NaCl(s) has been added. Assume that no volume change occurs.

(iii) If 0.100 M NaCl(aq) is added slowly to a beaker containing both 0.120 M AgNO3(aq) and 0.150 M

Pb(NO3)2(aq) at 25°C, which will precipitate first, AgCl(s) or PbCl2(s)? Show calculations to

support your answer.




Answer EITHER Question 2 below OR Question 3 printed on page 8. Only one of these two questions will begraded. If you start both questions, be sure to cross out the question you do not want graded. The Section II scoreweighting for the question you choose is 20 percent.

2 NO(g) + O2(g) → 2 NO2(g) ∆H° = −114.1 kJ, ∆S° = −146.5 J K−1

2. The reaction represented above is one that contributes significantly to the formation of photochemical smog.

(a) Calculate the quantity of heat released when 73.1 g of NO(g) is converted to NO2(g).

(b) For the reaction at 25�C, the value of the standard free-energy change, DG�� is �70.4 kJ.

(i) Calculate the value of the equilibrium constant, Keq , for the reaction at 25°C.

(ii) Indicate whether the value of DG� would become more negative, less negative, or remain unchangedas the temperature is increased. Justify your answer.�

(c) Use the data in the table below to calculate the value of the standard molar entropy, S�� for O2(g) at 25�C.

Standard Molar Entropy, S�(J K-1 mol-1)

NO(g) 210.8

NO2(g) 240.1

(d) Use the data in the table below to calculate the bond energy, in kJ mol-1, of the nitrogen-oxygen bond in NO2 . Assume that the bonds in the NO2 molecule are equivalent (i.e., they have the same energy).

Bond Energy

(kJ mol-1)

Nitrogen-oxygen bond in NO 607

Oxygen-oxygen bond in O2 495

Nitrogen-oxygen bond in NO2 ?




3. Answer the following questions about acetylsalicylic acid, the active ingredient in aspirin.

(a) The amount of acetylsalicylic acid in a single aspirin tablet is 325 mg, yet the tablet has a mass of 2.00 g.Calculate the mass percent of acetylsalicylic acid in the tablet.

(b) The elements contained in acetylsalicylic acid are hydrogen, carbon, and oxygen. The combustion of 3.000 gof the pure compound yields 1.200 g of water and 3.72 L of dry carbon dioxide, measured at 750. mm Hgand 25°C. Calculate the mass, in g, of each element in the 3.000 g sample.

(c) A student dissolved 1.625 g of pure acetylsalicylic acid in distilled water and titrated the resulting solution tothe equivalence point using 88.43 mL of 0.102 M NaOH(aq). Assuming that acetylsalicylic acid has onlyone ionizable hydrogen, calculate the molar mass of the acid.

(d) A 2.00 � 10-3 mole sample of pure acetylsalicylic acid was dissolved in 15.00 mL of water and then titratedwith 0.100 M NaOH(aq). The equivalence point was reached after 20.00 mL of the NaOH solution hadbeen added. Using the data from the titration, shown in the table below, determine

(i) the value of the acid dissociation constant, Ka , for acetylsalicylic acid and

(ii) the pH of the solution after a total volume of 25.00 mL of the NaOH solutionhad been added (assume that volumes are additive).

Volume of0.100 M NaOH

Added (mL) pH

0.00 2.22

5.00 2.97

10.00 3.44

15.00 3.92

20.00 8.13

25.00 ?




CHEMISTRY

Part BTime—50 minutes

NO CALCULATORS MAY BE USED FOR PART B.

Answer Question 4 below. The Section II score weighting for this question is 15 percent.

4. Write the formulas to show the reactants and the products for any FIVE of the laboratory situations describedbelow. Answers to more than five choices will not be graded. In all cases, a reaction occurs. Assume thatsolutions are aqueous unless otherwise indicated. Represent substances in solution as ions if the substances areextensively ionized. Omit formulas for any ions or molecules that are unchanged by the reaction. You need notbalance the equations.

Example: A strip of magnesium is added to a solution of silver nitrate.

(a) Sulfur dioxide gas is bubbled into distilled water.

(b) A drop of potassium thiocyanate solution is added to a solution of iron(III) nitrate.

(c) A piece of copper wire is placed in a solution of silver nitrate.

(d) Solutions of potassium hydroxide and propanoic acid are mixed.

(e) A solution of iron(II) chloride is added to an acidified solution of sodium dichromate.

(f) Chlorine gas is bubbled through a solution of potassium bromide.

(g) Solutions of strontium nitrate and sodium sulfate are mixed.

(h) Powdered magnesium carbonate is heated strongly.




Your responses to the rest of the questions in this part of the examination will be graded on the basis of the accuracyand relevance of the information cited. Explanations should be clear and well organized. Examples and equationsmay be included in your responses where appropriate. Specific answers are preferable to broad, diffuse responses.

Answer BOTH Question 5 below AND Question 6 printed on page 11. Both of these questions will be graded. TheSection II score weighting for these questions is 30 percent (15 percent each).

5. Answer the questions below that relate to the five aqueous solutions at 25�C shown above.

(a) Which solution has the highest boiling point? Explain.

(b) Which solution has the highest pH? Explain.

(c) Identify a pair of the solutions that would produce a precipitate when mixed together. Write the formula ofthe precipitate.

(d) Which solution could be used to oxidize the Cl-(aq) ion? Identify the product of the oxidation.

(e) Which solution would be the least effective conductor of electricity? Explain.




3 I-(aq) + S2O82-(aq) � I3

-(aq) + 2 SO42-(aq)

6. Iodide ion, I-(aq), reacts with peroxydisulfate ion, S2O82-(aq), according to the equation above. Assume that

the reaction goes to completion.

(a) Identify the type of reaction (combustion, disproportionation, neutralization, oxidation-reduction,precipitation, etc.) represented by the equation above. Also, give the formula of another substance that couldconvert I-(aq) to I3

-(aq).

(b) In an experiment, equal volumes of 0.0120 M I-(aq) and 0.0040 M S2O82-(aq) are mixed at 25�C. The

concentration of I3-(aq) over the following 80 minutes is shown in the graph below.

(i) Indicate the time at which the reaction first reaches completion by marking an “X” on the curve aboveat the point that corresponds to this time. Explain your reasoning.

(ii) Explain how to determine the instantaneous rate of formation of I3-(aq) at exactly 20 minutes. Draw

on the graph above as part of your explanation.

(c) Describe how to change the conditions of the experiment in part (b) to determine the order of the reactionwith respect to I-(aq) and with respect to S2O8

2-(aq).

(d) State clearly how to use the information from the results of the experiments in part (c) to determine the valueof the rate constant, k, for the reaction.

(e) On the graph below (which shows the results of the initial experiment as a dashed curve), draw in a curve forthe results you would predict if the initial experiment were to be carried out at 35�C rather than at 25�C.




Answer EITHER Question 7 below OR Question 8 printed on page 13. Only one of these two questions will begraded. If you start both questions, be sure to cross out the question you do not want graded. The Section II scoreweighting for the question you choose is 15 percent.

7. Answer the following questions that refer to the galvanic cell shown in the diagram above. (A table of standardreduction potentials is printed on the green insert and on page 4 of the booklet with the pink cover.)

(a) Identify the anode of the cell and write the half-reaction that occurs there.

(b) Write the net ionic equation for the overall reaction that occurs as the cell operates and calculate the valueof the standard cell potential, Ecell

� .

(c) Indicate how the value of Ecell would be affected if the concentration of Ni(NO3)2(aq) was changed

from 1.0 M to 0.10 M and the concentration of Zn(NO3)2(aq) remained at 1.0 M. Justify your answer.

(d) Specify whether the value of Keq for the cell reaction is less than 1, greater than 1, or equal to 1. Justifyyour answer.



13

8. Account for each of the following observations about pairs of substances. In your answers, use appropriateprinciples of chemical bonding and/or intermolecular forces. In each part, your answer must include referencesto both substances.

(a) Even though NH3 and CH4 have similar molecular masses, NH3 has a much higher normal boiling point

(�33�C) than CH4 (�164�C).

(b) At 25�C and 1.0 atm, ethane (C2H6) is a gas and hexane (C6H14) is a liquid.

(c) Si melts at a much higher temperature (1,410�C) than Cl2 (�101�C).

(d) MgO melts at a much higher temperature (2,852�C) than NaF (993�C).

END OF EXAMINATION

2001 ap chemistry questions - college board€¦ · · 2017-06-30ap chemistry 2001 free-response...

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