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PART 1 (white) Attempt these questions first Semester 1, 2017

17312

Foundations of Chemistry IA CHEM 1101 Foundations of Chemistry IA (Vet Bio) CHEM 1511

104266

10 mins 180 mins 190 mins

Official Reading Time: Writing Time: Total Duration: Part

Section

Questions

Time

1

A

Answer all questions

20 mins

10 marks

B

Answer all questions

25 mins

15 marks

C

Answer all questions

25 mins

15 marks

D

Answer all questions

25 mins

15 marks

E

Answer all questions

25 mins

15 marks

120 mins

70 marks total

HAND UP PART 1 (ALL WHITE PAGES) AFTER 2 HOURS

Marks

Instructions      



This is a Closed Book examination. Begin with Part 1. Part 1 (all white pages) will be collected after 2 hours. Part 2 is non-compulsory if both lecture tests were completed. Candidates who don’t intend to answer Part 2 can leave the exam after 2 hours. Answer Part 1, Section A & Part 2 on the appropriate Multiple Choice Answer Sheets provided. Note the instructions on the top of the answer sheets. These sections are NOT FOR PUBLICATION. Answers to Part 1, Sections B, C, D and E are to be written in SEPARATE booklets. In all your answers, indicate your reasoning and make clear (in words or by a diagram) the meaning of any symbols you introduce. Candidates are instructed to write in an easily legible, clearly expressed and grammatically correct manner. The mark given to your answer will depend on the quality of the reasoning displayed and on indications of conceptual understanding in addition to the factual material presented. Examination materials must not be removed from the examination room.

Materials     

4 Green books for Part 1. Calculators are permitted for the processing of numerical information. They must not be capable of remote communication, not have been programmed nor may they store additional information. CAS calculators not permitted. Molecular models are permitted. Printed Translation dictionary permitted. Three tables are provided separately: (i) Physical Constants and Reference Formulae, (ii) table of electronegativity and (iii) A Periodic Table of the Elements.

DO NOT COMMENCE WRITING UNTIL INSTRUCTED TO DO SO Course ID. 17312, 104266

Page 1 of 11

Foundations of Chemistry IA – June 2017

THIS PAGE IS INTENTIONALLY LEFT BLANK

Course ID. 17312, 104266

Page 2 of 11

Foundations of Chemistry IA – June 2017

PART 1, SECTION A MULTIPLE CHOICE QUESTIONS NOT FOR PUBLICATION

THESE QUESTIONS ARE COMPULSORY ANSWER ON THE WHITE MULTIPLE CHOICE ANSWER SHEET PROVIDED LABELLED ‘PART 1’. Each Question = 1 mark

THIS SECTION HAS BEEN REMOVED

Course ID. 17312, 104266

Page 3 of 11

Foundations of Chemistry IA – June 2017

SECTION B. ANSWER IN A SEPARATE BOOK. Question 1 (a)

Classify each of the following as either a mixture or a pure substance. For each substance, state whether it is an element or a compound.

For each mixture, state whether it is

homogeneous or heterogeneous. (i)

a lead weight

(ii)

calcium chloride (CaCl2) [2 marks]

(b)

18

Consider the atom O (oxygen-18). (i)

How many protons are in the nucleus?

(ii)

How many neutrons are in the nucleus?

(iii) How many electrons does the atom contain? [2 marks] (c)

What is the chemical formula for magnesium carbonate? [1 mark] [Question 1 total = 5 marks]

Question 2 (a)

Write Lewis (electron dot) structures for the following: (i)

S2–

(ii)

Be [2 marks]

(b)

Name the following compounds: (i)

H2SO4

(ii)

Fe(OH)3

(iii) CS2 [3 marks] [Question 2 total = 5 marks] Question 3 (a)

How many moles of hydrogen are present in a 65.0 g sample of methane (CH4)? [2 marks]

(b)

What is the concentration (in mol L-1) of a solution prepared from 0.5930 g of lithium phosphate (Li3PO4) in 125.0 mL of water? [3 marks] [Question 3 total = 5 marks] [Part B total = 15 marks] END OF SECTION B

Course ID. 17312, 104266

Page 6 of 11

Foundations of Chemistry IA – June 2017

SECTION C. ANSWER IN A SEPARATE BOOK. Question 1 The electron configuration for O is 1s22s22p4. (a)

Draw the full orbital box diagram for O that obeys the Pauli exclusion principle and Hund’s rule. [2 marks]

(b)

Are O atoms paramagnetic or diamagnetic? How many unpaired electrons does an O atom have? [1 mark]

(c)

In most ionic compounds, O exists as the oxide anion, O2–. Comment on this observation with reference to the electron configuration of O2–. [1 mark] [Question 1 total = 4 marks]

Question 2 For the methylamine molecule CH3NH2: H3C-NH2 (a)

Draw the Lewis structure (note there are two central atoms C and N). [1 mark]

(b)

Is methylamine a polar molecule? Explain using the structure you have drawn in (a). [1 mark]

(c)

Use VSEPR theory to determine the molecular geometry about the C and N atoms. [2 marks] [Question 2 total = 4 marks]

Question 3 (a)

Draw a Lewis structure of the carbonate anion, CO32–, and use resonance theory to explain why the carbon-oxygen bonds in CO32– are of equal length. [3 marks]

(b)

What is the bond order of the carbon-oxygen bonds in CO32–? [1 mark] [Question 3 total = 4 marks]

Course ID. 17312, 104266

Page 7 of 11

Foundations of Chemistry IA – June 2017

Question 4 List all the intermolecular forces that occur within each of the following (provide an explanation for your answers): (a)

Argon

Ar

(b)

Hydrogen fluoride

HF

(c)

Methane

CH4 [Question 4 total = 3 marks] [Section C total = 15 marks] END OF SECTION C

Course ID. 17312, 104266

Page 8 of 11

Foundations of Chemistry IA – June 2017

SECTION D. ANSWER IN A SEPARATE BOOK. Question 1 Write the equilibrium constant expression for the following reactions: (a)

N2(g) + 3H2(g)  2NH3(g)

(b)

2NO2(g)  N2O4(g)

(c)

CaCO3(s) + CO2(g) + H2O(l)  Ca2+(aq) + 2HCO32-(aq)

(d)

CaCO3(s) + SO2(g)  CaSO3(s) + CO2(g) [4 marks]

Question 2 Consider the following gas-phase reaction in a sealed flask of fixed volume, which has K = 85.0 at 460oC: SO2(g) + NO2(g)  NO(g) + SO3(g). (a)

At the same temperature, for the following concentrations of the gas, is the system at equilibrium? Justify your answer. [SO2] = 0.00250 M, [NO2] = 0.00350 M, [NO] = 0.0250 M, [SO3] = 0.0400 M [2 marks]

(b)

If the system is not at equilibrium, which direction will the reaction have to proceed to reach equilibrium? Explain your answer. [2 marks]

Question 3 Use Le Châtelier’s Principle to explain what will happen to the number of moles of SO3(g) in the flask in question 2 at equilibrium when: (a)

SO2(g) is added to the flask, but the volume is unchanged

(b)

the volume of the flask is decreased

(c)

the temperature is increased (given that the reaction is endothermic) [3 marks]

Question 4 For the situations in question 3, list those (e.g. “(a) and (b)” or “(c) only”) where; (i)

the equilibrium constant, K, will change.

(ii)

the reaction quotient, Q, will change (before there is time for any reaction to occur). [2 marks]

Question 5 Determine whether or not a precipitate of CaF2(s) will form when 250 mL of 0.020 M CaSO4(aq) is mixed with 250 mL of 0.050 M NaF(aq). Explain your reasoning. The Ksp for CaF2 is 3.2 x 10-11. [2 marks] [Section D total = 15 marks] END OF SECTION D Course ID. 17312, 104266

Page 9 of 11

Foundations of Chemistry IA – June 2017

SECTION E. ANSWER IN A SEPARATE BOOK. Question 1 (a)

(i)

Write a balanced equation that reflects hydrocyanic acid (HCN) acting as an acid with water. [1 mark]

(ii)

Identify the acid, base, conjugate acid and conjugate base in the reaction above. [1 mark]

(b)

For the reaction in part (a), write an expression for the acid dissociation constant, Ka. [1 marks]

(c)

Calculate the Kb of the cyanide ion (CN–), given that the pKa of hydrocyanic acid is 9.21. [2 marks]

(d)

At equilibrium, the concentration of hydronium ions (H3O+) in a 1.00 M solution of hydrocyanic acid at 25°C is 2.48 x 10-5 M. What is the concentration of hydroxide ions (OH–)? [1 mark]

(e)

What is the pH of the solution in part (d)? [1 mark] [Total for Question 1 = 7 marks]

Question 2 (a)

State what is meant by the term buffer solution. [1 mark]

(b)

Name or provide the formula of a reagent that could be added to a solution of acetic acid (CH3COOH) in order to form a buffer solution. [1 mark]

(c)

Calculate the pH of a buffer solution that is made up of 0.400 M HClO and 0.550 M NaClO. The pKa of HClO is 7.54. [1 mark] [Total for Question 2 = 3 marks]

Course ID. 17312, 104266

Page 10 of 11

Foundations of Chemistry IA – June 2017

Question 3 (a)

(i)

Write a balanced equation for the reaction of NaOH(aq) with HCl(aq). [1 mark]

(ii)

17.3 mL of 0.625 M NaOH (a strong base) was required to reach the equivalence point when titrated against 25.0 mL of an HCl solution (a strong acid). What is the concentration of the HCl solution? [2 marks]

(b)

Which of the following indicators would be most appropriate to estimate the position of the equivalence point in a titration of NaOH (a strong base) with formic acid (a weak acid)? Explain your answer. Methyl orange (Ka = 4.0 x 10-4) Phenolpththalein (Ka = 8.0 x 10-10) [2 marks] [Total for Question 3 = 5 marks] [Total for Part E = 15 marks]

END OF SECTION E

END OF EXAMINATION PART 1

Course ID. 17312, 104266

Page 11 of 11

Redeemable

PART 2 (sand) Attempt these questions AFTER completing Part 1 Semester 1, 2017

17312

Foundations of Chemistry IA CHEM 1101 Foundations of Chemistry IA (Vet Bio) CHEM 1511

104266 Official Reading Time: Writing Time: Total Duration: Part 2

10 mins 180 mins 190 mins Questions

Time

Marks

Answer all questions

60 mins

30 marks

(Non-compulsory if both lecture tests were completed)

Instructions     



This is a Closed Book examination. Begin with Part 1. Part 1 (all white pages) will be collected after 2 hours. Part 2 is non-compulsory if both lecture tests were completed. Candidates who don’t intend to answer Part 2 can leave the exam after 2 hours. Answer Part 1, Section A & Part 2 on the appropriate Multiple Choice Answer Sheets provided. Note the instructions on the top of the answer sheets. These sections are NOT FOR PUBLICATION. In all your answers, indicate your reasoning and make clear (in words or by a diagram) the meaning of any symbols you introduce. Candidates are instructed to write in an easily legible, clearly expressed and grammatically correct manner. The mark given to your answer will depend on the quality of the reasoning displayed and on indications of conceptual understanding in addition to the factual material presented. Examination materials must not be removed from the examination room.

Materials    

Calculators are permitted for the processing of numerical information. They must not be capable of remote communication, not have been programmed nor may they store additional information. CAS calculators are not permitted. Molecular models are permitted. Printed Translation dictionary permitted. Three tables are provided separately: (i) Physical Constants and Reference Formulae, (ii) table of electronegativity and (iii) A Periodic Table of the Elements.

DO NOT COMMENCE WRITING UNTIL INSTRUCTED TO DO SO

Course ID. 17312, 104266

Page 1 of 10

Foundations of Chemistry IA – June 2017

PART 2 MULTIPLE CHOICE QUESTIONS NOT FOR PUBLICATION If you do not attempt this section, your mark for Lecture Tests #1 & #2 will be used automatically for this section. If you sat Lecture Tests #1 & #2 and also attempt these questions, your best total mark of the two overall results will be counted. If you did not sit either or both Lecture Tests #1 & #2, you should attempt ALL questions in this section.

ANSWER ON THE SAND MULTIPLE CHOICE ANSWER SHEET PROVIDED LABELLED ‘PART 2’. Each Question = 1 mark

THIS SECTION HAS BEEN REMOVED

Course ID. 17312, 104266

Page 2 of 10

Foundations of Chemistry IA – June 2017

END OF PART 2

END OF EXAMINATION PAPER

Course ID. 17312, 104266

Page 10 of 10

Foundations of Chemistry IA

JUNE 2017

Tables for: CHEM 1101 Foundations of Chemistry IA, CHEM 1511 Foundations of Chemistry IA (Vet Bio)

Physical Constants and Reference Formulae

Avogadro’s Number

N = 6.023 × 1023 mol1

pH = log10[H3O+]

Henderson-Hasselbach Equation

 base  pH  pK a  log10   acid  

[H3O+] = 10pH

Table of Electronegativity H 2.2 Li 1.0 Na 0.93 K 0.82 Rb 0.82 Cs 0.79

Course ID. 17312, 104266

Be 1.6 Mg 1.3 Ca 1.3 Sr 0.95 Ba 0.89

B 2.0 Al 1.6 Ga 1.6 In 1.8 Tl 2.0

C 2.6 Si 1.9 Ge 2.0 Sn 2.0 Pb 2.3

N 3.0 P 2.2 As 2.2 Sb 2.1 Bi 2.0

O 3.4 S 2.6 Se 2.6 Te 2.1 Po 2.0

F 4.0 Cl 3.2 Br 3.0 I 2.7

Page 1 of 2

Foundations of Chemistry IA

JUNE 2017

Periodic Table of the Elements 1

18

1

H

2

2

13

14

15

16

17

1.008

He 4.003

4

5

6

7

8

9

10

Li

Be

B

C

N

O

F

Ne

6.941

9.012

10.811

12.011

14.007

15.999

18.998

20.180

3

11

12

Na

Mg

22.990

24.305

19

20

3 21

4 22

5 23

6 24

7 25

8 26

9 27

10 28

11 29

12 30

13

14

15

16

17

18

Al

Si

P

S

Cl

Ar

26.982

28.086

30.974

32.065

35.453

39.948

31

32

33

34

35

36

K

Ca

Sc

Ti

V

Cr

Mn

Fe

Co

Ni

Cu

Zn

Ga

Ge

As

Se

Br

Kr

39.098

40.078

44.956

47.867

50.942

51.996

54.938

55.845

58.933

58.693

63.546

65.39

69.723

72.64

74.922

78.96

79.904

83.80

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

Rb

Sr

Y

Zr

Nb

Mo

Tc

Ru

Rh

Pd

Ag

Cd

In

Sn

Sb

Te

I

Xe

85.468

87.62

88.906

91.224

92.906

95.94

101.07

102.91

106.42

107.87

112.41

114.82

118.71

121.76

127.60

126.90

131.29

55

56

57

72

73

74

75

76

77

78

79

80

81

82

83

84

85

86

Cs

Ba

La

Hf

Ta

W

Re

Os

Ir

Pt

Au

Hg

Tl

Pb

Bi

Po

At

Rn

132.91

137.33

138.91

178.49

180.95

183.84

186.21

190.23

192.22

195.08

196.97

200.59

204.38

207.2

208.98

110

111

112

113

114

116

117

64

65

66

67

68

70

71

87

88

89

104

105

106

107

108

109

Fr

Ra

Ac

Rf

Db

Sg

Bh

Hs

Mt

58

59

60

61

62

63

Pm

Course ID 17312, 104266

Ce

Pr

Nd

140.12

140.91

144.24

90

91

92

Th

Pa

U

232.04

231.04

238.03

69

Sm

Eu

Gd

Tb

Dy

Ho

Er

Tm

Yb

Lu

150.36

151.96

157.25

158.93

162.50

164.93

167.26

168.93

173.04

174.97

93

94

95

96

97

98