FA2008FNL

Chemistry 110 Name _______________________

Final Exam Form A Section _______________________

December 17, 2008 Signature _______________________

IMPORTANT: On the scantron (answer sheet), you MUST clearly fill your name, your student number, section number, and test form (white cover = test form A; yellow cover = test form B). Use a #2 pencil.

There are 40 questions on this exam. Check that you have done all of the problems and filled in the first 40 bubbles on the scantron. The maximum score on this exam is 40 points. Your score will be reported in percents (max 100%).

Exam policy

• This cover sheet must be signed and handed in with your answer sheet for your exam to count.

• Calculators with text-programmable memory are not allowed. • Relevant data and formulas, including the periodic table, are attached at the end of

this exam. • Your grade will be based only on what is on the scantron form. • The answer key will be posted on the web after the exam (under "Exam

Schedule").

Hints

• As you read the question, underline or circle key words to highlight them for yourself. Avoid errors from "mis-reading" the question.

• Pay attention to units and magnitudes (decimal places) of numbers obtained from calculations.

• There is no penalty for guessing.

CHEMISTRY 110 FINAL EXAM Dec. 17, 2008

FORM A ------------------------------------------------------------------------------------------------------------ 1. Below are the wavelengths of light emitted from various sources. Which one emits

photons with the highest energy?

A. Ar laser 489 nm B. Hg emission 436 nm C. Na vapor lights 589.6 nm D. distant star 1350 nm E. Mg vapor 285.2 nm

------------------------------------------------------------------------------------------------------------ 2. Which one of the following ions has the electron configuration [Ar] 3d7?

A. Ni2+ B. Co2+ C. Cr2+ D. Fe2+ E. Ca2+

------------------------------------------------------------------------------------------------------------ 3. In which subshell is an electron with the following quantum numbers found?

n = 2, l = 1, ml = 0, ms = –½

A. 1s B. 2p C. 3s D. 2s E. 2d

------------------------------------------------------------------------------------------------------------ 4. Which of these substances does not have hydrogen bonding as one of its

intermolecular forces?

CH3CH2NH2 CH3CH2OH CH3C H

O

CH3C OH

OA. B. C. D.

E. They all have hydrogen bonding as an intermolecular force.

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------------------------------------------------------------------------------------------------------------ 5. Ozone, the principal gas that diminishes harmful radiation from reaching the earth’s

surface, has the molecular formula O3. What is the molecular geometry of ozone?

A. tetrahedral B. trigonal planar C. bent D. linear E. T-shaped

------------------------------------------------------------------------------------------------------------ 6. Acetylene has the molecular formula C2H2. What is the hybridization of the carbon

atoms and how many π bonds are present in the molecule?

Hybridization π bonds A. sp2 2 B. sp 1 C. sp 2 D. sp2 3 E. sp3 4

------------------------------------------------------------------------------------------------------------ 7. How much heat is required to convert an 8.75 kg iceberg at −15.0°C to liquid water at

75.0°C? Cice = 2.09 J/g K ΔHfusion = 6.03 kJ/mol Cwater = 4.184 J/g K ΔHvaporization = 40.65 kJ/mol

A. 7338 kJ B. 1859 kJ C. 728 kJ D. 2090 kJ E. 5951 kJ

------------------------------------------------------------------------------------------------------------ 8. Compressed natural gas (methane) is used as an alternative fuel to gasoline. If a 20.0L

cylinder of compressed natural gas at 197 atm is opened to the atmosphere (at 1.12 atm), what volume of gas is released? Assume that the temperature remains constant at 25°C.

A. 2.12 × 102 L B. 1.11 ×101 L C. 4.41 × 102 L D. 3.52 × 103 L E. 6.78 × 102 L

------------------------------------------------------------------------------------------------------------

------------------------------------------------------------------------------------------------------------ 9. What is the correct equilibrium-constant expression for the reaction below?

(NH4)2Se (s) 2NH3 (g) + H2Se (g)

A. Keq= [NH

3]2[H

2Se]

B. Keq=[NH

3][H

2Se]

[(NH4)2Se]

C. Keq=[(NH

4)2Se]

[NH3]2[H

2Se]

D. Keq=

1

[(NH4)2Se]

E. Keq=[NH

3]2[H

2Se]

[(NH4)2Se]

------------------------------------------------------------------------------------------------------------ 10. At 2000°C, the equilibrium constant for the reaction

N2 (g) + O2 (g) 2 NO (g)

is Keq = 4.10 × 10−4. At equilibrium, ___________.

A. the products dominate. B. the concentration of reactants is greater than product concentration. C. approximately equal molar amounts of reactants and products are present. D. only products exist. E. only reactants exist.

------------------------------------------------------------------------------------------------------------ 11. For which of the following reactions would the equilibrium concentrations NOT be

affected by a change in the pressure caused by a change in volume?

A. PCl3 (g) + Cl2 (g) PCl5 (g)

B. 2 NO2 (g) N2 (g) + 2 O2 (g) C. N2 (g) + 3 H2 (g) 2 NH3 (g)

D. CO (g) + H2O (g) CO2 (g) + H2 (g) E. CO (g) + ½ O2 (g) CO2 (g)

------------------------------------------------------------------------------------------------------------

------------------------------------------------------------------------------------------------------------ 12. Acetic acid is a weak acid that dissociates into the acetate ion and a proton in

aqueous solution:

CH3COOH (aq) CH3COO– (aq) + H+ (aq)

At equilibrium at 25°C, a 0.100 M solution of acetic acid has the following concentrations:

[CH3COOH] = 0.0990 M [CH3COO–] = 1.33 × 10–3 M

[H+] = 1.33 × 10–3 M

What is the equilibrium constant for the ionization of acetic acid at 25°C?

A. 5.71 × 104 B. 0.100 C. 1.75 × 10–7 D. 1.79 × 10–5 E. 5.71 × 106

------------------------------------------------------------------------------------------------------------ 13. Rank the CO bond lengths in the following molecules, from longest to shortest:

CH3OH CO2 CO3

2–

A. CH3OH = CO2 > CO32–

B. CH3OH > CO2 > CO32–

C. CO32– = CH3OH > CO2

D. CH3OH > CO32– > CO2

E. CO32– > CO2 > CH3OH

------------------------------------------------------------------------------------------------------------ 14. An unknown ionic compound containing only O and another element has a melting

point greater than CaO’s melting point. Which one of following elements is in the compound?

A. Na B. K C. Mg D. Sr E. Rb

------------------------------------------------------------------------------------------------------------

------------------------------------------------------------------------------------------------------------ 15. What is the correct ranking of the labeled bond angles in order from smallest to

largest.

C

O

H3C C

H

CH3

CH2 O H

I II III

A. I < II < III B. III < II < I C. I < III < II D. II < III < I E. I = II < III

------------------------------------------------------------------------------------------------------------ 16. What is the mass % of nitrogen in the molecule shown below?

A. 41.2% B. 33.5% C. 30.4% D. 28.9% E. 26.9%

------------------------------------------------------------------------------------------------------------ 17. A 1.367 g sample of an organic compound was combusted in a stream of air to yield

3.002 g CO2 and 1.640 g H2O. If the original compound contained only C, H and O, what is its empirical formula?

A. C3H8O B. C2H6O C. C2H4O D. CH2O E. C3H6O2

------------------------------------------------------------------------------------------------------------ 18. What is the mass of 3.2 × 1020 water molecules?

A. 5.3 × 10−4 g B. 3.2 × 10−3 g C. 3.2 × 1020 g D. 9.6 × 10−3 g E. 5.8 × 1021 g

------------------------------------------------------------------------------------------------------------

N

NN

N

O

O

Go on to the next page

------------------------------------------------------------------------------------------------------------ 19. Which of the molecules below are polar?

I TeF4 II CH4 III XeI4

A. I only B. II only C. III only D. I and III E. I, II, and III

------------------------------------------------------------------------------------------------------------ 20. Distillation is a method by which ocean water is converted to drinking water by

selective vaporization of the solvent. A 2.5 L sample of ocean water containing 0.48 M NaCl is reduced to 0.5 L after evaporating 2.0 L of pure water from the solution. What is the concentration of NaCl in the remaining brine water?

A. 3.8 M B. 1.3 M C. 2.4 M D. 0.075 M E. 0.57 M

------------------------------------------------------------------------------------------------------------ 21. Rank the following three compounds in terms of increasing solubility in

cyclohexane, which is shown to the right.

C5H12 KCl C2H5OH

A. C2H5OH < C5H12 < KCl B. C5H12 < C2H5OH < KCl C. KCl < C5H12 < C2H5OH D. KCl < C2H5OH < C5H12 E. C2H5OH < KCl < C5H12

------------------------------------------------------------------------------------------------------------


------------------------------------------------------------------------------------------------------------ The following gases are in a single bulb at constant temperature and pressure. Use the following information to answer the next two questions.

Ptotal = 735 torr; Vtotal = 2.75 L; T = 320 K

Xi Pi H2 0.070 ??? CO ??? 254 torr Xe 0.030 22 torr N2 0.100 ??? Cl2 ??? ???

------------------------------------------------------------------------ 22. Which of the gases has the greatest average root mean squared speed?

A. Xe B. H2 C. Cl2 D. CO E. N2

------------------------------------------------------------------------ 23. What is the mole fraction of Cl2 gas in the flask?

A. 0.200 B. 0.346 C. 0.564 D. 0.454 E. 0.800

------------------------------------------------------------------------------------------------------------ 24. What is the longest wavelength that is able to break a single C–Cl bond in a

chlorofluorocarbon that has a bond energy of 177 kJ/mol?

A. 80.3 nm B. 144 nm C. 453 nm D. 567 nm E. 676 nm

------------------------------------------------------------------------------------------------------------


------------------------------------------------------------------------------------------------------------ 25. The complete combustion of ethanol is described by the following reaction:

C2H5OH (l) + 3 O2 (g) → 2 CO2 (g) + 3 H2O (l) ΔHrxn = –1366.7 kJ

Calculate the heat released by the combustion of 1.00 g of ethanol.

A. –7.10 kJ B. –29.7 kJ C. –42.7 kJ D. –137 kJ E. –1366.7 kJ

------------------------------------------------------------------------------------------------------------ 26. Calculate the heat of formation, ΔHf°, of C6H12O6 (s) from the following data. C6H12O6 (s) + 6 O2 (g) → 6 CO2 (g) + 6 H2O (l) ΔHrxn = –2803 kJ

ΔHf° of CO2 (g) = –393.5 kJ/mol ΔHf° of H2O (l) = –285.8 kJ/mol

A. –659.0 kJ/mol B. –985.4 kJ/mol C. –1273 kJ/mol D. –2803 kJ/mol E. There is not enough information to solve this problem.

------------------------------------------------------------------------------------------------------------ 27. Calculate ΔH for the reaction, 2 CO (g) + O2 (g) → 2 CO2 (g) ΔHrxn = ________

given the following chemical equations and their respective enthalpy changes: (1) C (s) + O2 (g) → CO2 (g) ΔH1 = –393.5 kJ (2) 2 C (s) + O2 (g) → 2 CO (g) ΔH2 = –221.0 kJ

A. –110.5 kJ B. –221.0 kJ C. –435.0 kJ D. –566.0 kJ E. –1010.0 kJ

------------------------------------------------------------------------------------------------------------


------------------------------------------------------------------------------------------------------------ 28. A typical car holds 60 L of octane (C8H18, density = 0.64 kg/L). If this entire amount of

fuel is completely combusted in air, what volume of CO2 is produced at 25°C and 1 atm?

A. 1.3 × 104 L B. 6.6 × 104 L C. 8.5 × 103 L D. 4.2 × 104 L E. 8.2 × 102 L

------------------------------------------------------------------------------------------------------------ 29. Which atom is being oxidized in the unbalanced reaction shown below?

SeO32− (aq) + I− (aq) + H+ (aq) → Se (s) + I2 (aq) + H2O (l)

A. Se in SeO3

2− B. I in I− C. H in H+ D. O in SeO3

2− E. None of these. This is not an oxidation reduction reaction.

------------------------------------------------------------------------------------------------------------ 30. The reaction below is used to produce methanol:

CO (g) + 2 H2 (g) → CH3OH (l) ΔHrxn = −128 kJ

Calculate the C–H bond energy, given the following data:

Bond D (kJ/mol) C≡O 1072

HH 436 C=O 614 CO 358 OH 463

A. 417 kJ/mol B. 374 kJ/mol C. 687 kJ/mol D. 272 kJ/mol E. 264 kJ/mol

------------------------------------------------------------------------------------------------------------


------------------------------------------------------------------------------------------------------------ 31. What spectator ions are present when aqueous ammonium phosphate reacts with

aqueous calcium nitrate?

A. PO43− only

B. NH4+ and NO3

− C. Ca2+ and PO4

3− D. Ca2+ and NH4

+ E. Ca2+, NH4

+ and NO3−

------------------------------------------------------------------------------------------------------------ 32. When an excited electron in the n = 6 shell of a hydrogen atom decays to the n = 5

shell, a photon is emitted. What is the energy change for this electronic transition?

A. −2.18 × 10−19 J B. 1.96 × 10−20 J C. 3.56 × 10−19 J D. −2.66 × 10−20 J E. −1.96 × 10−20 J

------------------------------------------------------------------------------------------------------------ 33. For the following ions, which of the statements below is true?

Br− Se2− Rb+ As3−

I. all of these are isoelectronic II. Rb+ has the smallest diameter III. As3− has the largest effective nuclear charge IV. all of these have the same number of protons

A. I and II only B. II and III only C. I and IV only D. I, II and III only E. I, II, III, and IV

------------------------------------------------------------------------------------------------------------


------------------------------------------------------------------------------------------------------------ 34. A closed vessel at 400 K is charged with 1.00 atm of Br2 (g), 1.00 atm of Cl2 (g), and

2.00 atm of BrCl (g). Which of the following statements is true?

Br2 (g) + Cl2 (g) 2BrCl (g) Kp = 7.0

A. The equilibrium partial pressures of Br2, Cl2, and BrCl will be the same as

the initial values. B. The equilibrium partial pressure of Br2 will be greater than 1.00 atm. C. At equilibrium, the total pressure in the vessel will be less than the initial

total pressure. D. The equilibrium partial pressure of BrCl (g) will be greater than 2.00 atm. E. The reaction will go to completion because there are equal amounts of Br2

and Cl2. ------------------------------------------------------------------------------------------------------------ 35. At elevated temperatures, molecular hydrogen and molecular bromine react to

partially form hydrogen bromide:

H2 (g) + Br2 (g) 2HBr (g) Kc = 0.293

If 162 g of HBr is placed in a 2.00 L reaction vessel, what is the [Br2] at equilibrium?

A. 2.54 M B. 0.269 M C. 0.394M D. 0.541 M E. 0.459 M

------------------------------------------------------------------------------------------------------------ 36. 25.0 mg of insulin (a nonelectrolyte) was dissolved in 25.0 mL of solution. The

osmotic pressure of this solution was then measured at 25°C and found to be 3.20 torr. What is the molecular weight of insulin?

A. 4.5 × 102 g/mol B. 8.7 × 102 g/mol C. 3.9 × 103 g/mol D. 5.8 × 103 g/mol E. 5.7 × 105 g/mol

------------------------------------------------------------------------------------------------------------


------------------------------------------------------------------------------------------------------------ 37. One mole of NH3 (g) and 1 mole of O2 (g) react in a vessel. Which one of the

following statements is true?

4 NH3 (g) + 5 O2 (g) → 4 NO (g) + 6 H2O (g) A. 1 mole of O2 (g) remains in the vessel. B. 1 mole of NO (g) is formed. C. All of the NH3 (g) is consumed. D. 1.2 moles of H2O (g) forms E. The total moles of gases in the vessel after the reaction is complete is 2

moles. ------------------------------------------------------------------------------------------------------------ 38. If 75.0 mL of 0.084 M HCl is titrated with 32.2 mL of 0.55 M NaOH, what is the

concentration of NaCl in the resulting solution?

A. 0.13 M B. 0.038 M C. 0.012 M D. 0.059 M E. 0.089 M

------------------------------------------------------------------------------------------------------------ 39. When 2.50 g of NaCl in aqueous solution are reacted with an excess of aqueous

AgNO3, a precipitate forms. A student performs this reaction, filters and dries the precipitate, then determines the mass of precipitate recovered to be 2.01 g. What is the percent yield for the reaction?

A. 32.5% B. 40.8% C. 60.8% D. 65.4% E. 80.4%

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------------------------------------------------------------------------------------------------------------ 40. 200 mL of 1 M HCl (aq) is combined with 200 mL of 1 M NaOH (aq) resulting in a

temperature increase of 6.50°C in the final solution. What is the enthalpy change for the following reaction per mole of H2O?

NaOH (aq) + HCl (aq) → NaCl (aq) + H2O (l) ΔHrxn = _______

Assume that the specific heat and density of the final solution are 4.18 J/g-°C and 1.00 g/mL, respectively.

A. –11.0 kJ B. –16.3 kJ C. –27.2 kJ D. –43.5 kJ E. –54.3 kJ

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