Topics in the June 2014 Exam Paper for CHEM1001

Click on the links for resources on each topic.

2014-J-2: Molecules and IonsChemical EquationsStoichiometry

2014-J-3: Lewis Model of Bonding

2014-J-4: Gas Laws

2014-J-5: Gas LawsThermochemistry

2014-J-6: Lewis Model of BondingVSEPR

2014-J-7: Lewis Model of BondingTypes of Intermolecular Forces

2014-J-8: VSEPRChemical Equilibrium

2014-J-9: Lewis Model of BondingThe Periodic Table

2014-J-10: Introduction to ElectrochemistryElectrochemistryElectrolytic Cells

2014-J-11: ThermochemistryFirst Law of Thermodynamics

2014-J-12: First Law of Thermodynamics

June 2014

2201(a) THE UNIVERSITY OF SYDNEY

FUNDAMENTALS OF CHEMISTRY 1A - CHEM1001 FIRST SEMESTER EXAMINATION

CONFIDENTIAL JUNE 2014 TIME ALLOWED: THREE HOURS GIVE THE FOLLOWING INFORMATION IN BLOCK LETTERS

FAMILY NAME

SID NUMBER

OTHER NAMES

TABLE NUMBER

INSTRUCTIONS TO CANDIDATES

• All questions are to be attempted. There are 19 pages of examinable material.

• Complete the written section of the examination paper in INK.

• Read each question carefully. Report the appropriate answer and show all relevant working in the space provided.

• The total score for this paper is 100. The possible score per page is shown in the adjacent tables.

• Each new short answer question begins with a •.

• Only non-programmable, University- approved calculators may be used.

• Students are warned that credit may not be given, even for a correct answer, where there is insufficient evidence of the working required to obtain the solution.

• Numerical values required for any question, standard electrode reduction potentials, a Periodic Table and some useful formulas may be found on the separate data sheets.

• Pages 15, 20, 22 and 24 are for rough working only.

OFFICIAL USE ONLY Multiple choice section

Marks Pages Max Gained

2-9 28

Short answer section Marks

Page Max Gained Marker

10 6

11 6

12 7

13 6

14 8

16 5

17 7

18 8

19 8

21 6

23 5

Total 72

Check Total

CHEM1001 2014-J-2 2201(a)

Page Total: Page total:

• Complete the following table by filling in the compound name or formula as required. Marks

4 Name Formula

CuSO4

NaNO3

magnesium chloride

iron(III) oxide

• What is the molarity of the solution formed when 0.50 g of aluminium fluoride is dissolved in 800.0 mL of water?

2

Answer:

What is [F–] in this solution?

Answer:

THE REMAINDER OF THIS PAGE IS FOR ROUGH WORKING ONLY.

CHEM1001 2014-J-3 2201(a)

Page Total: Page total:

• Explain, using words and diagrams, the type of bonding present in lithium oxide and compare this to the type of bonding in carbon dioxide.

Marks 6

Carbon and oxygen can also react to form carbon monoxide. Draw the Lewis structure of this molecule.

Explain any difference in the polarity of carbon monoxide and carbon dioxide.

CHEM1001 2014-J-4 2201(a)

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• Hydrazine (N2H4) reacts with dinitrogen tetraoxide (N2O4) to produce nitrogen and water, all in the gas phase, according to the following unbalanced equation.

N2H4(g) + N2O4(g) → N2(g) + H2O(g) Balance the above equation.

Marks 7

Describe the physical characteristics of a gas and sketch how the atoms of gaseous nitrogen might be represented in a container.

1.00 L of hydrazine was mixed with 1.00 L of dinitrogen tetraoxide at 25 °C and 1.00 atm pressure. Briefly explain Avogadro's Law and determine the mole ratio of hydrazine to dinitrogen tetraoxide present at room temperature?

Using the ideal gas equation, calculate the number of moles of hydrazine gas under these conditions.

Answer:

THIS QUESTION IS CONTINUED ON THE NEXT PAGE.

CHEM1001 2014-J-5 2201(a)

Page Total: Page total:

If the pressure remains constant at 1.00 atm, calculate the volume occupied by this mixture of gases after it was heated to 305 °C, before any reaction takes place.

Marks 6

Answer:

The molar heat capacity of N2H4 is 63 J K–1 mol–1 and that of N2O4 is 77 J K–1 mol–1. Calculate the heat capacity of this mixture.

Answer:

Calculate the energy required to heat this mixture from 25 °C to 305 °C.

Answer:

Calculate the maximum mass of nitrogen gas that could be produced in this reaction.

Answer:

CHEM1001 2014-J-6 2201(a)

Page Total: Page total:

• Complete the following table. The central atom is underlined. Marks

8 Species Lewis structure Molecular geometry

NH3

SO3

ICl3

ICl4–

CHEM1001 2014-J-7 2201(a)

Page Total: Page total:

• Complete the Lewis structure of formic acid below by adding double bond(s) and lone pair(s).

Marks 5

Formic acid can form dimers in which two molecules are paired by mutual hydrogen bonding. Draw a dimer of formic acid, clearly showing the hydrogen bonds between the molecules.

Formic acid may lose H+ from the oxygen to give a formate ion, shown in Equation 1.

HCOOH(aq) HCOO–(aq) + H+(aq) Equation 1

Draw a Lewis structure of the formate ion and use it to illustrate the concept of resonance.

Comment on the carbon-oxygen bond lengths in formic acid and the carbon-oxygen bond lengths in the formate ion.

THIS QUESTION IS CONTINUED ON THE NEXT PAGE.

CHEM1001 2014-J-8 2201(a)

Page Total: Page total:

What is the molecular geometry of the formate ion? Marks 7

Write the equilibrium constant expression for Equation 1.

At equilibrium at 25 °C, the amount of formate ion formed from a 0.100 M solution of formic acid is 4.2 %. Calculate the concentration of H+(aq) in this solution.

Answer:

Calculate the value of the equilibrium constant, K, for Equation 1 at this temperature.

Answer:

Hence calculate the concentration of formate ion in a 0.500 M solution of formic acid.

Answer:

CHEM1001 2014-J-9 2201(a)

Page Total: Page total:

• By adding double bonds and lone pairs, complete the structural formula of the molecule caffeine below.

Marks 2

• Briefly discuss the relationship between the electron configuration of an element and its position in the Periodic Table. 6

Carbon and lead are both in Group 14. One is a non-metal and the other is a metal. Outline one physical and one chemical characteristic of a non-metal and a metal and explain the reason for the trend from one to another in Group 14.

Non-metal Metal

Physical characteristic

Chemical characteristic

Explanation for trend in Group 14

CHEM1001 2014-J-10 2201(a)

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• Rechargeable nickel-cadmium batteries normally operate (discharge) with the following oxidation and reduction half-cell reactions.

Cd(OH)2(s) + 2e– → Cd(s) + 2OH–(aq) E° (1) = –0.82 V

AlF63–(aq) + 3e– → Al(s) + 6F–(aq) E° (2) = –2.07 V

Write out a balanced overall cell reaction.

Marks 8

Calculate the overall cell potential under standard conditions.

Answer:

A constant current of 3.15 A is measured during the operation of this cell. What would be the change in mass of the aluminium electrode after 10.0 minutes?

Answer:

Write out the overall cell reaction that would occur spontaneously if half-cell (1) were coupled to a standard hydrogen electrode (SHE).

What would be the cell potential for this new cell?

Answer:

CHEM1001 2014-J-11 2201(a)

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• Combustion of 15.0 g of coal provided sufficient heat to increase the temperature of 7.5 kg of water from 286 K to 298 K. Calculate the amount of heat (in kJ) absorbed by the water. The heat capacity of water, Cp° = 4.2 J K–1 g–1.

Marks 3

Answer:

Assuming that coal is pure carbon, calculate the heat of combustion (in kJ mol–1) of the coal.

Answer:

• The standard enthalpy of formation of SO2(g) is the enthalpy change that accompanies which reaction?

3

Calculate the standard enthalpy of formation of SO2(g) given the following data.

SO2(g) + 1/2O2(g) → SO3(g) ΔH = –99 kJ mol–1

S(s) + 3/2O2(g) → SO3(g) ΔH = –396 kJ mol–1

Answer:

CHEM1001 2014-J-12 2201(a)

Page Total: Page total:

• The standard heat of formation of ClF3(g) is –159 kJ mol–1. Use the bond enthalpies below to calculate the average Cl–F bond enthalpy in ClF3(g).

Marks 4

Bond Cl–Cl F–F

Bond enthalpy / kJ mol–1 243 158

Answer:

Explain why this number is different from the average Cl–F bond enthalpy estimated for ClF5(g) of 151 kJ mol–1.

• Explain the observation that the boiling point of ethanol is much higher than that of dimethyl ether despite these compounds having the same molar mass.

1

compound formula boiling point / °C

ethanol CH3CH2OH 78.3

dimethyl ether CH3OCH3 –22.0

2201(b) June 2014 CHEM1001 – FUNDAMENTALS OF CHEMISTRY 1A

DATA SHEET

Physical constants Avogadro constant, NA = 6.022 × 1023 mol–1 Faraday constant, F = 96485 C mol–1 Planck constant, h = 6.626 × 10–34 J s Speed of light in vacuum, c = 2.998 × 108 m s–1 Rydberg constant, ER = 2.18 × 10–18 J Boltzmann constant, kB = 1.381 × 10–23 J K–1 Permittivity of a vacuum, ε0 = 8.854 × 10–12 C2 J–1 m–1 Gas constant, R = 8.314 J K–1 mol–1 = 0.08206 L atm K–1 mol–1 Charge of electron, e = 1.602 × 10–19 C Mass of electron, me = 9.1094 × 10–31 kg Mass of proton, mp = 1.6726 × 10–27 kg Mass of neutron, mn = 1.6749 × 10–27 kg

Properties of matter Volume of 1 mole of ideal gas at 1 atm and 25 °C = 24.5 L Volume of 1 mole of ideal gas at 1 atm and 0 °C = 22.4 L Density of water at 298 K = 0.997 g cm–3 Conversion factors 1 atm = 760 mmHg = 101.3 kPa = 1.013 bar 1 Ci = 3.70 × 1010 Bq 0 °C = 273 K 1 Hz = 1 s–1 1 L = 10–3 m3 1 tonne = 103 kg 1 Å = 10–10 m 1 W = 1 J s–1 1 eV = 1.602 × 10–19 J 1 J = 1 kg m2 s–2

Decimal fractions Decimal multiples Fraction Prefix Symbol Multiple Prefix Symbol

10–3 milli m 103 kilo k 10–6 micro µ 106 mega M 10–9 nano n 109 giga G 10–12 pico p 1012 tera T

2201(b) June 2014 CHEM1001 – FUNDAMENTALS OF CHEMISTRY 1A

Standard Reduction Potentials, E° Reaction E° / V Co3+(aq) + e– → Co2+(aq) +1.82 Ce4+(aq) + e– → Ce3+(aq) +1.72 MnO4

–(aq) + 8H+(aq) + 5e– → Mn2+(aq) + 4H2O +1.51 Au3+(aq) + 3e– → Au(s) +1.50 Cl2 + 2e– → 2Cl–(aq) +1.36 O2 + 4H+(aq) + 4e– → 2H2O +1.23 Pt2+(aq) + 2e– → Pt(s) +1.18 MnO2(s) + 4H+(aq) + e– → Mn3+ + 2H2O +0.96 NO3

–(aq) + 4H+(aq) + 3e– → NO(g) + 2H2O +0.96 Pd2+(aq) + 2e– → Pd(s) +0.92 NO3

–(aq) + 10H+(aq) + 8e– → NH4+(aq) + 3H2O +0.88

Ag+(aq) + e– → Ag(s) +0.80 Fe3+(aq) + e– → Fe2+(aq) +0.77 Cu+(aq) + e– → Cu(s) +0.53 Cu2+(aq) + 2e– → Cu(s) +0.34 BiO+(aq) + 2H+(aq) + 3e– → Bi(s) + H2O +0.32 Sn4+(aq) + 2e– → Sn2+(aq) +0.15 2H+(aq) + 2e– → H2(g) 0 (by definition) Fe3+(aq) + 3e– → Fe(s) –0.04 Pb2+(aq) + 2e– → Pb(s) –0.126 Sn2+(aq) + 2e– → Sn(s) –0.136 Ni2+(aq) + 2e– → Ni(s) –0.24 Co2+(aq) + 2e– → Co(s) –0.28 Cd2+(aq) + 2e– → Cd(s) –0.40 Fe2+(aq) + 2e– → Fe(s) –0.44 Cr3+(aq) + 3e– → Cr(s) –0.74 Zn2+(aq) + 2e– → Zn(s) –0.76 2H2O + 2e– → H2(g) + 2OH–(aq) –0.83 Cr2+(aq) + 2e– → Cr(s) –0.89 Al3+(aq) + 3e– → Al(s) –1.68 Sc3+(aq) + 3e– → Sc(s) –2.09 Mg2+(aq) + 2e– → Mg(s) –2.36 Na+(aq) + e– → Na(s) –2.71 Ca2+(aq) + 2e– → Ca(s) –2.87 Li+(aq) + e– → Li(s) –3.04

2201(b) June 2014 CHEM1001 – FUNDAMENTALS OF CHEMISTRY 1A

Useful formulas

Quantum Chemistry

E = hν = hc/λ

λ = h/mv

E = –Z2ER(1/n2)

Δx⋅Δ(mv) ≥ h/4π

q = 4πr2 × 5.67 × 10–8 × T4

T λ = 2.898 × 106 K nm

Electrochemistry

ΔG° = –nFE°

Moles of e– = It/F

E = E° – (RT/nF) × lnQ

E° = (RT/nF) × lnK

E = E° – 0.0592n

logQ (at 25 °C)

Acids and Bases

pH = –log[H+]

pKw = pH + pOH = 14.00

pKw = pKa + pKb = 14.00

pH = pKa + log{[A–] / [HA]}

Gas Laws

PV = nRT

(P + n2a/V2)(V – nb) = nRT

Ek = ½mv2

Radioactivity

t½ = ln2/λ

A = λN

ln(N0/Nt) = λt 14C age = 8033 ln(A0/At) years

Kinetics

t½ = ln2/k k = Ae–Ea/RT

ln[A] = ln[A]0 – kt

2

1 1 2

1 1ln = - ( )ak Ek R T T

Colligative Properties & Solutions

Π = cRT

Psolution = Xsolvent × P°solvent c = kp

ΔTf = Kfm

ΔTb = Kbm

Thermodynamics & Equilibrium

ΔG° = ΔH° – TΔS°

ΔG = ΔG° + RT lnQ

ΔG° = –RT lnK

ΔunivS° = R lnK

Kp = Kc100( )

nRT Δ

Miscellaneous

A = –log0

II

A = εcl

E = –A2

04erπε

NA

Mathematics

If ax2 + bx + c = 0, then x = 2b b 4ac

2a− ± −

ln x = 2.303 log x

Area of circle = πr2

Surface area of sphere = 4πr2

PER

IOD

IC T

AB

LE

OF T

HE

EL

EM

EN

TS

1

2 3

4 5

6 7

8 9

10 11

12 13

14 15

16 17

18

1 H

YD

RO

GE

N

H

1.008

2 H

EL

IUM

He

4.003 3

LIT

HIU

M

Li

6.941

4 B

ER

YL

LIU

M

Be

9.012

5 B

OR

ON

B

10.81

6 C

AR

BO

N

C

12.01

7 N

ITR

OG

EN

N

14.01

8 O

XY

GE

N

O

16.00

9 FL

UO

RIN

E

F 19.00

10 N

EO

N

Ne

20.18 11

SOD

IUM

Na

22.99

12 M

AG

NE

SIUM

Mg

24.31

13 A

LU

MIN

IUM

Al

26.98

14 SIL

ICO

N

Si 28.09

15 PH

OSPH

OR

US

P 30.97

16 SU

LFU

R

S 32.07

17 C

HL

OR

INE

Cl

35.45

18 A

RG

ON

Ar

39.95 19

POT

ASSIU

M

K

39.10

20 C

AL

CIU

M

Ca

40.08

21 SC

AN

DIU

M

Sc 44.96

22 T

ITA

NIU

M

Ti

47.88

23 V

AN

AD

IUM

V

50.94

24 C

HR

OM

IUM

Cr

52.00

25 M

AN

GA

NE

SE

Mn

54.94

26 IR

ON

Fe 55.85

27 C

OB

AL

T

Co

58.93

28 N

ICK

EL

Ni

58.69

29 C

OPPE

R

Cu

63.55

30 Z

INC

Zn

65.39

31 G

AL

LIU

M

Ga

69.72

32 G

ER

MA

NIU

M

Ge

72.59

33 A

RSE

NIC

As

74.92

34 SE

LE

NIU

M

Se 78.96

35 B

RO

MIN

E

Br

79.90

36 K

RY

PTO

N

Kr

83.80 37

RU

BID

IUM

Rb

85.47

38 ST

RO

NT

IUM

Sr 87.62

39 Y

TT

RIU

M Y

88.91

40 Z

IRC

ON

IUM

Zr

91.22

41 N

IOB

IUM

Nb

92.91

42 M

OL

YB

DE

NU

M

Mo

95.94

43 T

EC

HN

ET

IUM

Tc

[98.91]

44 R

UT

HE

NIU

M

Ru

101.07

45 R

HO

DIU

M

Rh

102.91

46 PA

LL

AD

IUM

Pd 106.4

47 SIL

VE

R

Ag

107.87

48 C

AD

MIU

M

Cd

112.40

49 IN

DIU

M

In 114.82

50 T

IN

Sn 118.69

51 A

NT

IMO

NY

Sb 121.75

52 T

EL

LU

RIU

M

Te

127.60

53 IO

DIN

E

I 126.90

54 X

EN

ON

Xe

131.30 55

CA

ESIU

M

Cs

132.91

56 B

AR

IUM

Ba

137.34

57-71 72

HA

FNIU

M

Hf

178.49

73 T

AN

TA

LU

M

Ta

180.95

74 T

UN

GST

EN

W

183.85

75 R

HE

NIU

M

Re

186.2

76 O

SMIU

M

Os

190.2

77 IR

IDIU

M

Ir 192.22

78 PL

AT

INU

M

Pt 195.09

79 G

OL

D

Au

196.97

80 M

ER

CU

RY

Hg

200.59

81 T

HA

LL

IUM

Tl

204.37

82 L

EA

D

Pb 207.2

83 B

ISMU

TH

Bi

208.98

84 PO

LO

NIU

M

Po [210.0]

85 A

STA

TIN

E

At

[210.0]

86 R

AD

ON

Rn

[222.0] 87

FRA

NC

IUM

Fr [223.0]

88 R

AD

IUM

Ra

[226.0] 89-103 104

RU

TH

ER

FOR

DIU

M

Rf

[263]

105 D

UB

NIU

M

Db

[268]

106 SE

AB

OR

GIU

M

Sg [271]

107 B

OH

RIU

M

Bh

[274]

108 H

ASSIU

M

Hs

[270]

109 M

EIT

NE

RIU

M

Mt

[278]

110 D

AR

MST

AD

TIU

M

Ds

[281]

111 R

OE

NT

GE

NIU

M

Rg

[281]

112 C

OPE

RN

ICIU

M

Cn

[285]

114

FLE

RO

VIU

M

Fl [289]

116

LIV

ER

MO

RIU

M

Lv

[293]

LAN

THA

NO

IDS

57 L

AN

TH

AN

UM

La

138.91

58 C

ER

IUM

Ce

140.12

59 PR

ASE

OD

YM

IUM

Pr 140.91

60 N

EO

DY

MIU

M

Nd

144.24

61 PR

OM

ET

HIU

M

Pm

[144.9]

62 SA

MA

RIU

M

Sm

150.4

63 E

UR

OPIU

M

Eu

151.96

64 G

AD

OL

INIU

M

Gd

157.25

65 T

ER

BIU

M

Tb

158.93

66 D

YSPR

OSIU

M

Dy

162.50

67 H

OL

MIU

M

Ho

164.93

68 E

RB

IUM

Er

167.26

69 T

HU

LIU

M

Tm

168.93

70 Y

TT

ER

BIU

M

Yb

173.04

71 L

UT

ET

IUM

Lu

174.97

AC

TINO

IDS

89 A

CT

INIU

M

Ac

[227.0]

90 T

HO

RIU

M

Th

232.04

91 PR

OT

AC

TIN

IUM

Pa [231.0]

92 U

RA

NIU

M

U

238.03

93 N

EPT

UN

IUM

Np

[237.0]

94 PL

UT

ON

IUM

Pu [239.1]

95 A

ME

RIC

IUM

Am

[243.1]

96 C

UR

IUM

Cm

[247.1]

97 B

ER

KE

LL

IUM

Bk

[247.1]

98 C

AL

IFOR

NIU

M

Cf

[252.1]

99 E

INST

EIN

IUM

Es

[252.1]

100 FE

RM

IUM

Fm

[257.1]

101 M

EN

DE

LE

VIU

M

Md

[256.1]

102 N

OB

EL

IUM

No

[259.1]

103 L

AW

RE

NC

IUM

Lr

[260.1]

2201(b) CHEM1001 – FUNDAMENTALS OF CHEMISTRY 1A June 2014