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THE UNIVERSITY OF MELBOURNE SCHOOL OF CHEMISTRY SEMESTER 1 EXAMINATION, 2017 SUBJECT: CHEMISTRY FOR BIOMEDICINE, CHEM10006 Student Number: ___________________________ Exam Duration: 3 hours

Reading Time: 15 minutes

This paper has 27 pages. Authorized materials: Unassembled molecular model kits. Casio FX82(any suffix) calculator ONLY. Note:

Calculators are permitted in accordance with the rules of the Faculty of Science. They may be used for the processing of numerical information only. They must not have been programmed nor should they store additional information. Calculators will be randomly checked during the course of the examination.

Instructions to Invigilators: Students will attempt Section A on the examination paper itself. For Section A, students must also enter their answers on the computer scan sheet provided. Please remind students to leave the exam paper and the scan sheet on their desk for collection at the end of the examination. A 14-page script book is required for Section B of the paper. Instructions to Students: This assessment consists of two sections, Section A and Section B. Section A carries one half of the total marks available while Section B carries the remaining half. It is suggested that you spend

equal time on each section. The marks available for each question are proportional to the suggested completion times given at the end of each question. You must answer Section A on the paper itself and also enter your answers on the computer scan sheet provided. Answer Section B in the examination script book provided. A table of selected physical constants, useful quantities and conversion factors is given in Appendix 1, structures of nucleobases in Appendix 2, structures of the 20 common amino acids in Appendix 3 and the D-aldohexose "family tree" in Appendix 4. Please ensure that the exam paper, the scan sheet and the script book used to answer Section B are all left on your desk at the end of the examination.

Paper to be held by Baillieu Library - YES

© 2017, The University of Melbourne

Page 1 of 27

CHEM10006 Semester 1, 2017

THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK

© 2017, The University of Melbourne

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CHEM10006 Semester 1, 2017

Student enrolment number....................................

SECTION A The suggested time for this section is 1.5 hours

Your answers to this section of the examination must be circled on this examination script, which must be handed in at the end of the examination period. You must also show your answers to this section, together with your student number, on the computer scan sheet provided. Please enter your student enrolment number in the spaces provided. In addition, ensure that your student enrolment number is recorded on each page of Section A.

A table of selected physical constants, useful quantities and conversion factors is provided at the end of the exam paper in Appendix 1, structures of nucleobases in Appendix 2, structures of the 20 common amino acids in Appendix 3 and the D-aldohexose "family tree" in Appendix 4.

Question A1. What is the overall change in internal energy, ∆E, for a system that undergoes the following two steps? Step 1: The system gives off 30.0 J of heat while performing 70.0 J of work. Step 2: The system absorbs 70.0 J of heat while 30.0 J of work is done on it.

A. 0.0 J

B. +200 J

C. +600 J

D. –60.0 J

E. +140.0 J (2 minutes)

Question A2. The heat capacity of liquid water is 75.4 J mol–1 K–1 while the enthalpy of fusion of ice is 6.020 kJ mol–1. What is the smallest number of ice cubes at 0°C, each containing 18 g of water, needed to cool 500.0 g of liquid water from 20°C to 0°C? A. 1

B. 7

C. 14

D. 15

E. 126 (3 minutes)

© 2017, The University of Melbourne

Page 3 of 27

CHEM10006 Semester 1, 2017

Question A3. When a 0.105 g sample of ethylene (C2H4) is burned in a calorimeter, the temperature increases by 2.14°C. Calculate the heat of combustion for one mole of ethylene if the heat capacity of the calorimeter is 2.47 kJ K–1. A. –5.29 kJ

B. –50.3 kJ

C. –572 kJ

D. 661 kJ

E. –1.41 × 103 kJ (3 minutes)

Question A4. Under which conditions must a reaction be spontaneous at all temperatures? A.

∆H is positive and ∆S is positive

B.

∆H = 0 and ∆S is negative

C.

∆S = 0 and ∆H is positive

D.

∆H is negative and ∆S is positive

E.

∆H is negative and ∆S is negative (2 minutes)

Question A5. For the reaction 2A + B → 2C, the following data are collected: [A]0

[B]0

Initial Rate

Expt. 1

0.10 M

0.20 M

300 M s−1

Expt. 2

0.30 M

0.40 M

3,600 M s−1

Expt. 3

0.30 M

0.80 M

14,400 M s−1

What is the rate law for the above reaction? A.

Rate = k [A]2 [B]

B.

Rate = k [A] [B]

C.

Rate = k [A] [B]2

D.

Rate = k [A]2 [B]2

E.

Rate = k [A]2 [B] / [C]2 (3 minutes)

© 2017, The University of Melbourne

Page 4 of 27

CHEM10006 Semester 1, 2017

Student enrolment number....................................

Question A6. The rate constant for a reaction increases from 10.0 s−1 to 100.0 s−1 when the temperature is increased from 27°C to 127°C. What is the approximate activation energy, assuming Arrhenius kinetics, for the reaction in kJ mol−1 ? A. 23.0

B. 12.7

C. 5.00

D. 18.3

E. 45.6 (3 minutes)

Question A7. For the reaction 2A + B → C, the following mechanism is proposed: Step 1:

A + B ⇌ D

(fast equilibrium)

Step 2:

D+B→E

(slow)

Step 3:

E+A→C+B

What is the rate law for the formation of C? A.

Rate = k [A]

B.

Rate = k [A]2 [B]

C.

Rate = k [A] 2 [B]2

D.

Rate = k [A] [B]

E.

Rate = k [A] [B]2 (3 minutes)

Question A8. Given that Kp = 18 (atm2) for the following equilibrium: NH4I(s) ⇌ NH3(g) + HI(g) Calculate the total pressure inside a sealed reaction vessel that initially contains only 10 g NH4I (s). (Assume that solid is present at all times) A. 4.3 atm

B. 8.5 atm

C. 2.1 atm

D. 18.0 atm

E. 6.3 atm (2 minutes)

© 2017, The University of Melbourne

Page 5 of 27

CHEM10006 Semester 1, 2017

Question A9. Consider the following statements about species present in the biogeochemical phosphorus cycle and the chemistry of phosphorus. I.

The shape of the phosphine molecule, PH3, may be described as trigonal planar.

II.

The dissolution of P4O10(s) in water to yield phosphoric acid, is a redox process.

III.

The P-P-P bond angle in white phosphorus, P4, is 90°.

IV.

For the polyphosphate ion [P3O10]n-, the numerical value of n is 5.

V.

When one molecule of ATP is converted to ADP one molecule of water is consumed and the sign of the free energy change for the process is positive in sign.

Which of the above statements are CORRECT? A.

I, II and III

B.

I, III and V

C.

IV

D.

III, IV and V

E.

V (2 minutes)

Question A10. Consider the following statements about species present in the biogeochemical carbon cycle and the chemistry of carbon. I. II.

Both carbon dioxide and carbon monoxide are non polar molecules. Carbon dioxide is more soluble in an aqueous sodium hydroxide solution than it is in water.

III.

In the photosynthesis reaction the conversion of CO2 to glucose C6H12O6 is a reduction reaction.

IV.

In the carbonate ion, CO32-, the hybridization at the carbon atom is sp3.

V.

The species C2H6+ is a radical.

Which of the above statements are CORRECT ? A.

I, II and III

B.

II, III and IV

C.

III, IV and V

D.

II, III and V

E.

III and V (2 minutes) © 2017, The University of Melbourne

Page 6 of 27

CHEM10006 Semester 1, 2017

Student enrolment number....................................

Question A11. Consider the following statements about species present in the biogeochemical nitrogen cycle and the chemistry of nitrogen. The hybridization at the nitrogen atoms in hydrazine, N2H4, is sp3.

I. II.

The molecules NO, NO2 and N2O4 are all radical species.

III.

The reaction of NO2 with water to form nitric acid, HNO3, is a redox reaction.

IV.

The nitrite ion, NO2 , is linear in shape.

-

The presence of NO2 in the upper atmosphere contributes to degradation of the ozone layer.

V.

Which of the above statements are CORRECT ? A.

III and IV

B.

I, II and III

C.

III, IV and V

D.

II, III and IV

E.

I, III and V (2 minutes)

The following information applies to Questions A12 and A13. The Kb of methylamine, CH3NH2, is 4.0 x 10-4. Question A12. The percentage dissociation of the CH3NH3+ cation in a 0.100 M aqueous solution of CH3NH3Cl will be closest to? A. 0.2 %

B. 6.3 %

C. 1.6 x 10−3 %

D. 4.0%

E. 2.5 % (2 minutes)

Question A13. The pH of a solution in which 0.010 mole of solid NaOH is dissolved in 300 mL of a 0.100 M solution of CH3NH3Cl will be closest to? (Assume no volume change occurs upon dissolution of the NaOH.) A. 10.6

B. 10.9

C. 10.3

D. 13.5

E. 5.8 (2 minutes)

© 2017, The University of Melbourne

Page 7 of 27

CHEM10006 Semester 1, 2017

Question A14. Consider the hydronium ion (H3O+) and the molecules carbon monoxide (CO) and methanal (H2CO). What is the hybridization at the oxygen atoms in these species? H3O+

CO

H2CO

A.

sp2

sp

sp2

B.

sp2

sp2

sp3

C.

sp3 sp

sp

sp2

sp2 sp

sp3 sp3

D. E.

sp3

(2 minutes)

The below molecule, Doxorubicin, is referred to in questions A15 – A17

*

Question A15. The structure of the anticancer drug Doxorubicin is shown above. How many sp3 hybridized carbon atoms are present in Doxorubicin? A. 10

B. 11

C. 12

D. 14

E. 15 (2 minutes)

Question A16. How many stereogenic centres are present in Doxorubicin? A. 5

B. 6

C. 7

D. 10

E. 12 (2 minutes)

Question A17. What is the configuration of the carbon in Doxorubicin that is labelled with an asterisk? A. (R)-

B. (S)-

C. (E)-

D. (R)- and (E)-

E. (S)- and (E)(2 minutes)

© 2017, The University of Melbourne

Page 8 of 27

CHEM10006 Semester 1, 2017

Student enrolment number....................................

Question A18. The following compounds are:

A.

Conformational Isomers

B.

Constitutional/Structural Isomers

C.

Enantiomers

D.

Diastereomers

E.

None of the above (2 minutes)

Question A19. The following compounds are:

A.

Enantiomers

B.

Constitutional/Structural isomers

C.

Cis/Trans isomers

D.

Identical molecules

E.

None of the above (2 minutes)

© 2017, The University of Melbourne

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CHEM10006 Semester 1, 2017

Question A20. In the lowest energy conformation of the compound below, how many alkyl substituents are axial?

A. 0

B. 1

C. 2

D. 4

E. 6 (2 minutes)

Question A21. Consider the following statements regarding the amino acids N-methyl-tryptophan (1) and N-methyl-tyrosine (2).

1

I.

2

Both amino acids are (S)-enantiomers

II.

Both amino acids are aromatic

III.

Both amino acids can be diastereomers

Which of the above statements are CORRECT? A.

I.

B.

II

C.

III

D.

I and II

E.

I, II and III (2 minutes)

© 2017, The University of Melbourne

Page 10 of 27

CHEM10006 Semester 1, 2017

Student enrolment number....................................

Question A22. Which one of the following alkenes would be predicted to give the most stable carbocation intermediate upon reaction in dilute H2SO4?

1

2

3

4

A. 1

B. 2

5

C. 3

D. 4

E. 5 (2 minutes)

Question A23. Which one of the alkenes in Question A22 above could give rise to the product shown below upon reaction in dilute H2SO4?

A. 3

B. 4 and 5

C. 3 and 5

D. 4

E. 5 (2 minutes)

Question A24. Which one of the following is the LEAST stable carbocation?

(2 minutes) © 2017, The University of Melbourne

Page 11 of 27

CHEM10006 Semester 1, 2017

The following scheme is referred to in questions A25 – A27 H Mechanism A:

HO

H Br

H

HO

H H3C Mechanism B:

H

HO

H H

H3C

+

Br

+

Br

CH3

Br CH3

CH3

O Mechanism C:

H H

+

H2O

O H3C

Cl

OH

+

Cl

HO

H3C Mechanism D:

HO

H3C

Cl CH3

CH3 HO CH3 H3C

+

Cl

Question A25. Which one of the mechanisms in the above scheme corresponds to that expected for an E2 reaction? A.

Mechanism A

B.

Mechanism B

C.

Mechanism C

D.

Mechanism D

E.

None of the above (2 minutes)

Question A26. Which one of the mechanisms in the above scheme corresponds to that expected for an SN1 reaction? A.

Mechanism A

B.

Mechanism B

C.

Mechanism C

D.

Mechanism D

E.

None of the above (2 minutes) © 2017, The University of Melbourne

Page 12 of 27

CHEM10006 Semester 1, 2017

Student enrolment number....................................

Question A27. In which one of the mechanisms in the above scheme is hydroxide ion not acting as a nucleophile? A.

Mechanism A

B.

Mechanism B

C.

Mechanism C

D.

Mechanism D

E.

None of the above (2 minutes)

Appendix B and the following information are required to answer questions A28 and A29: Amygdalin is a poisonous cyanogenic glycoside found in the kernels of bitter almonds. Although promoted as an alternative cancer treatment it has clinically been proven to be ineffective.

OH O

HO HO

O HO HO HO

O O OH C

Amygdalin

N

Question A28. Which one of the following statements is CORRECT? A.

Amygdalin is a reducing sugar with a 1,6 α glycosidic linkage.

B.

Amygdalin is a reducing sugar with a 1,6 β glycosidic linkage.

C.

Amygdalin is a non-reducing sugar with a 1,6 α glycosidic linkage.

D.

Amygdalin is a non-reducing sugar with a 1,6 β glycosidic linkage.

E.

None of the above. (3 minutes)

© 2017, The University of Melbourne

Page 13 of 27

CHEM10006 Semester 1, 2017

Question A29. Upon hydrolysis of Amygdalin, the following monosaccharides are formed: A.

D-allose and D-glucose

B.

D-gulose and D-glucose

C.

D-galactose and D-mannose

D.

D-allose and D-mannose

E.

D-glucose only (3 minutes)

Question A30. Which of the following four carbohydrates are D sugars? CHO CH2OH HO

H

CHO

H HOH 2C

CHO

CHO

HOH 2C

OH

H OH

H

OH

H

OH

H

CH2OH OH

I.

A. I and IV

II.

B. II and III

III.

C. I and III

D. IV

IV.

E. None are D sugars (2 minutes)

Question A31. Which one of the following statements about DNA is INCORRECT? A.

A nucleoside consists of: a five carbon monosaccharide, a phosphate and a heterocyclic base

B.

The classes of heterocyclic base found in DNA are purines and pyrimidines

C.

Bases pairing occurs between: guanine and cytosine; adenine and thymine

D.

In a nucleotide unit the components are sequentially linked by: phosphate— monosaccharide—heterocyclic base (3 minutes) © 2017, The University of Melbourne

Page 14 of 27

CHEM10006 Semester 1, 2017

Student enrolment number....................................

Question A32. The Ksp of CdII(OH)2 is 5.9 x 10-15. What is the [Cd2+]sat if the water pH is 6.0? A.

1.7 x 10-2 mol L-1

B.

59 mol L-1

C.

5.9 x 10-9 mol L-1

D.

5.9 x 10-3 mol L-1

E.

17 mol L-1 (2 minutes)

Question A33. Which one of the following octahedral complexes may exist in an enantiomeric form? en = ethylenediamine (1,2-diaminoethane) A.

trans–Co(NH3)4Cl2+

B.

mer-Ni(NH3)(H2O)32+

C.

fac-Cr(H2O)3Cl2

D.

trans-Mn(en)2(H2O)2

E.

Co(en)3 (2 minutes)

Question A34. Consider the following statements concerning haemoglobin and myoglobin. I.

O2 is bound more strongly to myoglobin than haemoglobin.

II.

Myoglobin can bind up to four O2 molecules at a...