2015 exam ver 1

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Chemistry 1AA3 Final Exam April 20, 2015 McMaster University VERSION 1

Instructors: D. Brock, J. Landry, P. Lock, H. Stöver Duration: 180 min.

This test contains 24 numbered pages printed on both sides. There are 35 multiple-choice questions appearing on pages numbered 3 to 20. Pages 21 and 22 are extra space for rough work. Page 23 includes some useful data and equations. There is a periodic table on page 24. You may tear off the last page to view the periodic table and to do your rough work. You must enter your name and student number on the question sheets, as well as on the answer sheet. Your invigilator will be checking your student card for identification. You are responsible for ensuring that your copy of the question paper is complete. Bring any discrepancy to the attention of your invigilator. All questions are each worth 2 marks; the total marks available are 70. There is no additional penalty for incorrect answers. BE SURE TO ENTER THE CORRECT VERSION OF YOUR TEST (shown near the top of page 1), IN THE SPACE PROVIDED ON THE ANSWER SHEET. ANSWER ALL QUESTIONS ON THE ANSWER SHEET, IN PENCIL. Instructions for entering multiple-choice answers are given on page 2. SELECT ONE AND ONLY ONE ANSWER FOR EACH QUESTION from the answers (A) through (E). No work written on the question sheets will be marked. The question sheets may be collected and reviewed in cases of suspected academic dishonesty. Academic dishonesty may include, among other actions, communication of any kind (verbal, visual, etc.) between students, sharing of materials between students, copying or looking at other students’ work. If you have a problem, please ask the invigilator to deal with it for you. Do not make contact with other students directly. Keep your eyes on your own paper - looking around the room may be interpreted as an attempt to copy. Only Casio FX 991 MS electronic calculators may be used; but they must NOT be transferred between students. Use of periodic tables or any aids, other than those provided, is not allowed.



OMR EXAMINATION - STUDENT INSTRUCTIONS NOTE: IT IS YOUR RESPONSIBILITY TO ENSURE THAT THE ANSWER SHEET IS PROPERLY COMPLETED: YOUT EXAMINIATION RESULT DEPENDS UPON PROPER ATTENTION TO THESE INSTRUCTIONS. The scanner, which reads the sheets, senses the bubble shaded areas by their non-reflection of light. A heavy mark must be made, completely filling the circular bubble, with an HB pencil. Marks made with a pen will NOT be sensed. Erasures must be thorough or the scanner will still sense a mark. Do NOT use correction fluid on the sheets. Do NOT put any unnecessary marks or writing on the sheet. 1. On SIDE 1 (red side) of the form, in the top box, in pen, print your student number,

name, course name, and the date in the spaces provided. Then you MUST write your signature, in the space marked SIGNATURE.

2. In the second box, with a pencil, mark your student number, exam version number in the space provided and fill in the corresponding bubble numbers underneath.

3. Answers: mark only ONE choice from the alternatives (A,B,C,D,E) provided for each question. The question number is to the left of the bubbles. Make sure that the number of the question on the scan sheet is the same as the number on the test paper.

4. Pay particular attention to the Marking+ Directions on the form. 5. Begin answering the question using the first set of bubbles, marked “1”.

Version number



1. A first-order reaction has a half-life of 28 s. What is k for the reaction? A) 38 s–1 B) 0.039 s–1 C) 0.025 s–1 D) 0.15 s–1 E) 0.0086 s–1

2. Cellulases are enzymes that hydrolyse cellulose into simpler carbohydrates. A cellulase has an activation energy of 75 kJ mol−1 at 65 °C. A newly developed cellulase increased the rate of cellulose hydrolysis 1000–fold under the same conditions. How much did the activation energy decrease, in kJ mol−1? A) 29 B) 34 C) 15 D) 25 E) 19

VERSION 1. Enter your version number in the correct column on

your scan sheet (see p. 2 for details).



3. Using the method of initial rates resulted in the following experimental data for the reaction: A + B + 2C → G + 2H v0 = k[A]a [B]b [C]c

Indicate the correct exponents (a, b, c) and rate constant, k:

Experiment [A]0 [B]0 [C]0 v0 (M s−1) 1 0.15 0.50 0.20 9.0 × 10−6

2 0.60 0.50 0.20 3.6 × 10−5

3 0.60 0.25 0.20 1.8 × 10−5

4 0.15 0.50 0.25 1.4 × 10−5

a b c k A) 1 2 2 3.0 × 10−3 B) 1 1 2 3.0 × 10−3 C) 2 1 1 3.0 × 10−3 D) 1 1 1 3.0 × 10−3 E) 1 2 1 1.5 × 10−3

4. Indicate the FALSE statement regarding the Michaelis-Menten expression. A) Enzymatic reactions are first order with respect to [S] when [S] = KM. B) When [S] << KM, doubling [S] will double v0. C) The values of both KM and kcat depend on the enzyme as well as substrate. D) Doubling [E]0 when [S] << KM will double v0. E) Comparing substrates A and B, the one with the higher KM value will require a

higher substrate concentration for the reaction to become pseudo-zero order.



5. The rate of the first order reaction A → P was followed by measuring the decrease in [A] over time. Indicate the correct rate constant, k, for this reaction.

Time (s) [A] (mol L–1) 0 0.35

100 0.29 300 0.20

1000 0.058

A) 0.0079 s−1 B) 0.00053 s−1 C) 0.00032 s−1 D) 0.0052 s−1 E) 0.0018 s−1

6. Indicate the FALSE statement regarding transition state theory. A) The highest energy point between reactants and products in an elementary process

is called its transition state. B) For an elementary process, the transition states for the forward and the reverse

steps have the same potential energy. C) A reactive intermediate can precede and/or follow a transition state. D) Only exothermic reactions can have transition states. E) The chemical species at the transition state is called the transition state species, or

the activated complex.



7. Indicate the FALSE statement below regarding the steady state assumption for the reaction:

A) If k1 << k2 and k2 << k3, then the rate expression simplifies to v0 = k1[A]. B) [I] depends on [A]. C) In the steady state approximation, [I] is constant over time. D) If k1 >> k3, then A → I must be the rate-limiting step. E) If k1 << k2, then [I] ≈ 0 throughout the reaction.

8. Indicate the FALSE statement regarding rates of chemical reactions. A) A plot of v0 versus [A] that is a horizontal line indicates a zero order reaction. B) Reactions that are first order with respect to A, become second order with respect

to A upon doubling the concentration of A. C) Comparing initial rates, v0, for different reagent concentrations can reveal

information about the order of the reaction. D) Rates may decrease, remain constant, or increase during a reaction. E) Reactions can slow down due to depletion of reagents, formation of inhibitors,

increasing contribution from reverse reactions, and deactivation of catalysts.

I Gk1k2

k3A



9. From the list below, choose the pieces of information related to the titration of a weak acid with a strong base that can be used, individually, to calculate the weak acid's Ka value. (i) the amount of strong base needed to reach the equivalence point (ii) the initial pH of the weak acid solution, provided its concentration is known (iii) the pH at the equivalence point, provided the concentration of the conjugate base

is known (iv) the pH at the half-equivalence point (v) the width of the buffer region A) i, ii, v B) ii, iii, v C) ii, iii, iv D) i, iv, v E) i, iii, iv

10. Which of the following combinations of aqueous solutions will result in the formation of a buffer? All solutions are 0.200 M. A) 100 mL CH3COONa + 5 mL HCl B) 35 mL NH3 + 15 mL HCl C) 10 mL NaOH + 25 mL NaNO2 D) 100 mL HNO3 + 50 mL CH3COONa E) 50 mL HClO4 + 25 mL NaOH



11. A student prepares 2.00 L of a solution containing 0.340 mol of sodium acetate (CH3COONa) and sufficient acetic acid (CH3COOH) to give pH 5.16. The student wishes to adjust the solution to pH 4.00. How many moles of HCl(g) must be added to the solution? (Assume no volume change on addition of gaseous HCl.) Data: Ka(CH3COOH) = 1.8 × 10–5

A) 0.86 B) 1.4 C) 0.59 D) 0.27 E) 0.13

12. A student reacts propene with either HCl or H2(g)/Pt. Rank the organic reactant and products in order of increasing boiling point.

A)

B)

C)

D) E)



13. Which of the following statements about phase diagrams is FALSE? A) The process of converting a solid to a liquid is called fusion or melting. B) At the triple point, converting a solid to a gas is endothermic. C) Along the curve between the triple point and the critical point, a liquid and gas are

in equilibrium. D) The normal melting point and normal boiling point of a substance vary with

pressure. E) At temperatures and pressures above the critical point a supercritical fluid is

formed.

14. What would the dominant intermolecular force be in a pure sample of liquid propan−2−ol? A) covalent bonding B) ion-ion C) ion-dipole D) hydrogen bonding E) dispersion



15. Indicate the FALSE statement regarding morphine, shown below.

A) Morphine contains an ester group. B) Morphine contains an amine group. C) Morphine contains a phenol group. D) There are exactly 8 sp2-hybridized atoms in morphine. E) Reacting morphine with excess acetic anhydride leads to formation of two ester

groups.

16. How many of the double bonds in the molecules below have an E-configuration?

A) 3 B) 5 C) 2 D) 1 E) 4



17. A student completes the synthesis of acetylsalicylic acid (aspirin; C9H8O4; experiment # 9). Weighing the recrystallized product indicates a 110 % yield, caused by the product still containing water. What is the minimum mole % of water in the product? A) 25 % B) 75 % C) 50 % D) 1 % E) 15 %

18. 2–Bromopropane was reacted with magnesium in diethyl ether, followed by addition of an equimolar amount of 2–butanone, and an acid workup. What was the name of the tertiary alcohol product? A) 2–methylbutan–2–ol B) 2,5–dimethylhexan–4–ol C) 3–methylheptan–3–ol D) 2,3–dimethylbutan–2–ol E) 2,3–dimethylpentan–3–ol



19. Which of the following statements about the reactivities of alkenes and alkynes is FALSE? A) Hydrogenation of an alkyne with Lindlar's catalyst leads to the Z-isomer. B) Complete combustion of oct-2-ene requires more oxygen than oct-2-yne. C) An alkene reacts with dilute H2SO4(aq) to produce an alcohol. D) Hydrogenation of propyne using a platinum catalyst yields propane. E) Hydrogenation of 1,2-dimethylcyclopentene yields the trans-isomer.

20. Which of the following molecular formulas could represent a compound that would show a peak in an IR spectrum corresponding to a carbonyl group (1650 to 1750 cm–1)? A) C4H11N B) C3H6O C) C2H6O2 D) C7H16 E) C5H12O



21. Which of the following reactions is CORRECTLY formulated? Only the main organic products are shown.

A) i, ii, iii B) ii, iv C) i, ii D) all are correctly formulated E) ii, iii

22. Select the FALSE statement about the following reaction.

The reaction: A) results in two organic products that are geometric isomers. B) has a multi-step reaction mechanism with a slow first step. C) proceeds via a carbocation intermediate. D) has a first-order rate law. E) produces a phenol.



23. Which word describes the conversion of ethanal to ethanol? A) substitution B) oxidation C) reduction D) hydrolysis E) hydration

24. Which of the following is NOT an alkane? A) C7H16 B) CH4 C) C2H6 D) C12H24 E) C4H10



25. Select the FALSE statement about organic chemistry reactions. A) Reduction of a ketone with NaBH4 followed by acid workup leads to a secondary

alcohol. B) Reaction of methanal with CH3MgBr followed by acid workup leads to methanol. C) A tertiary alkyl bromide can be converted to an alcohol by reaction with water. D) A carboxylic acid can be formed by the oxidation of a primary alcohol with a

strong oxidizer such as KMnO4(aq) in acid. E) Bimolecular nucleophilic substitution reactions proceed with inversion only.

26. Which of the following species are NOT intermediates or products in the acid-catalyzed hydration of 2-methyl-but-2-ene?

(i)

(ii)

(iii)

(iv)

A) ALL of i − iv B) NONE of i − iv C) i, iii D) ii, iii E) ii, iv



27. Which of the following is NOT a propagation or termination step of radical halogenation of ethane or radical polymerization of vinyl chloride? A) CH3CH3 + Cl· → HCl + CH3CH2· B) CH3CH2· + CH3CH2· → CH3CH2CH2CH3 C) RO−[CH2CH(Cl)]n· + CH2=CH(Cl) → RO−[CH2CH(Cl)]n+1· D) RO−[CH2CH(Cl)]n· + RO−[CH2CH(Cl)]m· → RO−[CH2CH(Cl)]n+m−OR E) Cl2 + H· → HCl + Cl·

28. Select the sequence of reagents/conditions needed to convert cyclohexane to the product shown.

A) Cl2, Δ Mg, ether propanal H3O+(aq) B) Cl2, hν NaOH(aq) 1−propanol H3O+(aq) C) Br2, Δ NaOH(aq) CH3CH(MgBr)CH3, ether H3O+(aq) D) HCl, hν Mg, ether propanone H3O+(aq) E) Cl2, hν Mg, ether propanone H3O+(aq)



29. Which of the following statements about hybridization is FALSE? A) Carbon is not the only atom that undergoes hybridization. B) The ideal angle between sp3-hybridized orbitals is 109.5°. C) Mixing three atomic orbitals always results in the formation of three hybrid

orbitals. D) In carbon, electrons in an sp2-hybridized orbital are higher in energy than those in

an sp-hybridized orbital. E) Energy is released when a carbon atom goes from a ground state (gas-phase)

electron configuration to a hybridized configuration.

30. Which of the following species is NOT aromatic? (Assume that if the molecule/ion can be planar in order to meet the criteria for aromaticity then it will be).

A)

B)

C)

D)

E)



31. Isoflavan has anti-inflammatory activity, but is too hydrophobic to be easily absorbed. A library is constructed, including the two compounds to the right. Indicate the size of the complete library of compounds accessible, assuming each substituent can be used at any site of diversity.

A) 245 B) 65 C) 254 D) 28 E) 81

32. Which of the following statements about aromaticity are FALSE? (i) Toluene (C6H5−CH3) is an aromatic molecule. (ii) The Hückel rule states that an aromatic system has 4n+2 π-bonds. (iii) Aromatic rings must contain 4 or more C atoms. (iv) An aromatic compound has a π-system with delocalized electrons. A) iii, iv B) i, ii C) ii, iv D) i, iii E) ii, iii



33. Indicate the FALSE statement about the planar molecule shown below.

This molecule: A) is aromatic. B) has a nitrogen atom that has a lone pair of electrons that is not part of the π-system. C) has 10 π electrons in its π system. D) has 2 sp2-hybridized nitrogen atoms. E) will readily undergo addition reactions across the C=C bond marked by x and y.

34. A combinatorial library was screened in 96 well plates for bactericidal antibiotics, that is, compounds that selectively kill bacteria without harming human cells. Which compound (I – V) is most likely to be a bactericidal antibiotic?

A) V B) III C) II D) I E) IV



35. A 96 well plate assay is used to screen a library of compounds for inhibitors of biliverdin reductase, an enzyme that converts green biliverdin to yellow bilirubin. Enzyme activity is assessed through disappearance of the green colour. By mistake, one of the sample wells did not receive the enzyme. Assuming the library compound added to this well was actually not an inhibitor, which of the following statements is TRUE? A) The result from this sample well cannot be defined in one of these ways. B) This sample well will produce a false positive result. C) This sample well will produce a true negative result. D) This sample well will produce a false negative result. E) This sample well will produce a true positive result.



Extra space for rough work.



General data and equations. Other data appear with the questions. There is a periodic table on the next page. STP = 273.15 K, 1 atm F = 96485 C mol−1

R = 8.3145 J K−1 mol−1 = 0.08206 L atm K−1 mol−1 NA = 6.022 × 1023 mol−1

1 atm = 760 mm Hg = 101.325 kPa 0 °C = 273.15 K

1 J = 1 kg m2 s−2 = 1 kPa L = 1 Pa m3 1 m = 109 nm = 1010 Å

1 cm3 = 1 mL 1 g = 103 mg

Kw = 1.0 × 10−14 1 mol = 103 mmol = 106 µmol

v0 = k[A]m[B]n dt

d[G]1 ΔtΔ[G]1

0

ggtlim

v =→

=

[A]t = [A]0•e−kt t[A][A]

0

t kln −=

[A]t = [A]0 − kt kk

t 693.02ln2/1 ==

v0 = k[A]2 or k[A][B] 0dtS]d[E =•

[S] [S][E]0

+=

M

catKkv0

/RTEaA −= ek


24 End of Exam

2015 exam ver 1

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