Chemistry 122Winter 2010Oregon State University

Exam 2February 25, 2010Dr. Robertha Howell

Dr. Richard Nafshun

Instructions: You should have with you several number two pencils, an eraser, your 3" x 5" note card, a calculator, and your University ID Card. If you have notes with you, place them in a sealed backpack and place the backpack OUT OF SIGHT or place the notes directly on the table at the front of the room.

Fill in the front page of the Scantron answer sheet with your last name, first name, middle initial, and student identification number. Leave the class section number and the test form number blank.

This exam consists of 25 multiple-choice questions. Each question has four points associated with it. Select the best multiple-choice answer by filling in the corresponding circle on the rear page of the answer sheet. If you have any questions before the exam, please ask. If you have any questions during the exam, please ask the proctor. Open and start this exam when instructed. When finished, place your Scantron form in the appropriate stack and present your University ID Card to the proctor. You may keep the exam packet, so please show your work and mark the answers you selected on it.

R = 0.0821 L•atm/mol•K / 760 mm Hg = 760 torr = 1 atm / m = mol/kg
M = mol/L / ΔTf = imkf / ΔTb = imkb
ΠV = nRT / kf (H2O) = 1.86 ºC/m / kb(H2O) = 0.512 ºC/m
/ SC: 2r = s BCC: 4r = s√3 FCC: 4r = s√2

1.Consider the phase diagrams below. Which of the following statements is correct?

Phase Diagram 1Phase Diagram 2

(A)Phase diagram 1 can accurately represent the phase diagram of carbon dioxide because it indicates that to prepare the liquid a moderate pressure needs to be applied

(B)Phase diagram 2 can accurately represent the phase diagram of carbon dioxide because the solid-liquid equilibrium line has a positive slope

(C)Neither of these diagrams accurately represents the phase diagram of carbon dioxide

2.Which of the following is a chemical compound in which the atoms are bonded by covalent bonds in a continuous network—in which there are no individual molecules and the entire crystal may be considered a macromolecule?

(A)Methane

(B)Sodium fluoride

(C)Soap

(D)Lithium

(E)Diamond

4.R• + CH2CH2→

(A)A soap

(B)A network covalent compound

(C)Ethene

(D)A polymer

(E)Quartz

5.Which of the following is false?

(A)O2 is more soluble than H2 in H2O because O2 is more polarizable

(B)The intermolecular force holding CH4 molecules together is primarily dispersion forces

(C)Ethanol (CH3CH2OH) is a polar molecule which exhibits hydrogen bonding with water

(D)Sodium fluoride melts at roughly the same temperature as magnesium oxide as they have similar molar masses

(E)Calcium chloride is an ionic compound

6.Calcium oxide melts near 2572 ºC. Magnesium oxide melts near 2852 ºC. The difference in melting points can be attributed to:

(A)Different intermolecular forces (dispersion, dipole-dipole, hydrogen bonding)

(B)Different ionic charges (+1, +2, +3, -1, -2, -3…)

(C)Different distances between nuclei (ionic size)

(D)Network covalent compounds

(E)One is a molecule (attractions by intermolecular forces), one is an ionic compound (attractions by charges)

7.Strontium chloride melts at 874 ºC. Strontium sulfide melts near 2000 ºC. The difference in melting points can be attributed to:

(A)Different intermolecular forces (dispersion, dipole-dipole, hydrogen bonding)

(B)Different ionic charges (+1, +2, +3, -1, -2, -3…)

(C)Different distances between nuclei (ionic size)

(D)Network covalent compounds

(E)One is a molecule (attractions by intermolecular forces), one is an ionic compound (attractions by charges)

8.Hexane, CH3CH2CH2CH2CH2CH3, melts at -95 ºC. Propane, CH3CH2CH3, melts at −188 °C. The difference in melting points can be attributed to:

(A)Differences in hydrogen bonding

(B)Differences in dipole-dipole forces

(C)Differences in dispersion forces

(D)One is a molecule (attractions by intermolecular forces), one is a network covalent compound

(E)One is a molecule (attractions by intermolecular forces), one is an ionic compound (attractions by charges)

9.Consider carbon tetrachloride, CCl4. The intermolecular forces present in liquid CCl4 are:

Carbon tetrachloride

(A)Dispersion forces only.

(B)Dipole-dipole forces only.

(C)Dispersion forces and dipole-dipole forces.

(D)Dispersion forces, dipole-dipole forces, and hydrogen bonding.

(E)Hydrogen bonding only.

10.Consider diamond, NaS, NaO, NaBr, He, and CH4. Arranged in increasing melting point, these are:

Lowest mpHighest mp

(A)diamond < NaS < NaO < NaBr < He < CH4

(B)He < CH4 < NaBr < NaO < NaS < diamond

(C)He < CH4 < NaO < NaS < NaBr < diamond

(D)He < CH4 < NaBr < NaS < NaO < diamond

(E)diamond < NaS < NaO < NaBr < CH4 < He

11.The equivalent number of atoms in the FCC unit cell is:

(A)1

(B)2

(D)4

(E)6

12.What intermolecular force or bond is primarily responsible for the solubility of CH3CH2OH in water?

(A)ion-dipole force

(B)dipole-dipole force

(C)ionic bonding

(D) covalent bonding

(E) hydrogen bonding

13.The structure below represents:

(A)An SC unit cell

(B)A BCC unit cell

(C)A FCC unit cell

(D)A prokaryotic cell

(E)A cell phone

14.The cubic form for the fictitious element Lady Gagaium is FCC. The atomic radius is 183.1 pm and the molar mass is 198.4 g/mol. The density of Lady Gagaium is:

[1 m = 1 x 1012 pm 1 m = 100 cm]

(A)15.10 g/cm3

(B)9.49 g/cm3

(D)10.73 g/cm3

(E)11.88 g/cm3

15.Ideally, colligative properties depend only on the

(A)concentration of solute particles in a solution.

(B)molar masses of the solute particles in a solution.

(C)density of a solution.

(D)hydrated radii of the molecules or ions dissolved in a solution.

(E)partial pressure of the gases above the surface of a solution.

16.The freezing point of1.25 m MgCl2 (aq) is:

(A)- 1.86 C

(B)- 2.45 C

(C)- 6.98 C

(D)- 13.7 C

(E)- 9.11 C

17.Which one of the following molecules will exhibit dipole-dipole intermolecular forces as a pure liquid (molecular geometries are given in brackets)?

(A)C2H2 (linear)

(B)SO3 (trigonal planar)

(C)CF4 (tetrahedral)

(D)F2 (linear)

(E)NO2 (bent)

18.A student dissolves 108.6 g of an unknown polymer in 1600 mL of water at 300 K. She measures the osmotic pressure to be 0.01634 mm Hg. What is the molar mass of the polymer?

(A)8.72 x 106 g/mol

(B)1.29 x 106 g/mol

(D)1.40 x 10-6 g/mol

(E)1.40 x 106 g/mol

19.Which of the following statements is false?

(A)Increasing the temperature of a reaction will increase the rate for exothermic reactions and decrease the rate for endothermic reactions.

(B)Increasing the number of collisions will increase the rate of reaction.

(C)Lowering the activation energy will increase the rate of reaction.

(D)The rate of reaction can only be determined through experimentation.

(E)The addition of a catalyst will increase the rate by lowering the activation energy of a process.

20.The half-life is:

(A)The amount of time required for half the sample to decay

(B)0.500 years

(C)The amount of time required for the entire sample to decay

(D)-k

(E)

21.A student () obtains a 100.0 gram sample of 139Ba (t1/2 = 83.06 minutes). How long will it take so that only 0.1000 grams of 139Ba remain?

(A)827.3 minutes

(B)796.8 minutes

(D)781.2 minutes

(E)857.5 minutes

22.Which graph could correctly depict the changes in concentrations for the

reaction 2 CH3OH (l) + 3 O2 (g) → 2 CO2(g) + 4 H2O (g)?

23.The following are initial rate data for:A + 2B  C

Experiment / Initial [A] / Initial [B] / Initial Rate
1 / 0.10 / 0.10 / 3.2
2 / 0.20 / 0.10 / 12.8
3 / 0.20 / 0.20 / 25.6
4 / 0.10 / 0.20 / 6.4

(A)The rate law is Rate = k[A]4[B]2.

(B)The rate law is Rate = k[A]0[B]2.

(C)The rate law is Rate = k[A]2[B]0.

(D)The rate law is Rate = k[A]2[B]1.

(E)The rate law is Rate = k[A]4[B]1.

24.Based on the thermodynamic data plotted below, the activation energy (Ea) for the

reaction A + B → C + D are:

(A)the activation energy (Ea) is +100 kJ/mol

(B)the activation energy (Ea) is +200 kJ/mol

(C)the activation energy (Ea) is +400 kJ/mol

(D)the activation energy (Ea) is +500 kJ/mol

(E)the activation energy (Ea) is +600 kJ/mol

25.So, the Chemistry 122 final exam is Tuesday, March 16, 2010 at 7:30 A.M. (Good Morning!) Later that day...

(A)I will be sleeping

(B)Vegas

(C)I will be at the registrar's office enrolling in six chemistry courses for the Spring term

(D)Two words: Twitter and Twinkiees

(E)I will be laying out on the grass. Looking up at the sky. Trying to envision each cloud as a piece of chemistry glassware.

[Understand this... since this notion in your psyche, every time you look

at a cloud you will smile and see an Erlenmeyer flask.]

[Any response will receive full credit; even no response]