Final-B KEY - Exam FINAL of Chem 200 SDSU PDF

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Exam FINAL of Chem 200 SDSU...

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Chem 200 Summer 2016

CHEM _______

Final - B

August 16, 2016

Lab Section Number: _____

Name (printed):_____________________________________________ Signature:______________________________________ This exam consists of 36 questions all of equal value for a total of 225 points. Make sure that your test has all of the pages. Please read each problem carefully. There are no intentionally misleading questions; each problem should be taken at its face value. Please mark your answers on the Scantron sheet provided to you and on the actual exam. You will be given a periodic table and an exam information sheet to use during the exam. You may remove it from the exam make it more accessible. You may also use the designated Casio fx-300ms-plus calculator or equivalent non-programmable non-graphing scientific calculator during the exam. Use the back pages of the test as scratch paper. You are not allowed to use any devices capable of accessing the internet, textbooks, notes, or homemade reference sheets during the exam. You may leave if you finish the exam early. Give the exam and the information sheet to your TA and leave quietly without disturbing other students. Before leaving, check that all your answers have been properly entered on the Scantron sheet and the exam and that your name is written on every page of the exam and on the Scantron sheet. All cell phones and electronic devices must be turned off and put away. Please remove all hats and caps. Place your books and all papers out of sight under your seat. If the TA believes that you might be looking at your neighbor’s paper, you will be asked to move to a new location. Exam scores will be posted on Blackboard as soon as the grading is complete. Your test will be returned to you in the first lab meeting of next week. If you have any questions regarding the grading of your exam, please notify your TA. The time available for the exam is 120 minutes. Good luck! 1  of 13

Chem 200 Summer 2016

Final - B

Name: ___________________________________________

August 16, 2016 Lab Section #: _______

Please mark your answers on the scantron sheet using a #2 pencil and also mark your answers on the exam itself. Mark the test form version “B” on your scantron. 1. Select the answer that expresses the result of this calculation with the correct number of significant figures and with correct units." 16.18 cm x 9.6114 g ÷ 1.4783 cm2 =# (a) (b) (c) (d) (e)

105.2 g/cm3 105.2 g/cm2 105.2 g/cm 72.13 g/cm2 72.13 g/cm

2. A normal breath takes in about 1.0 L of air. Assuming that air has an average molar mass of 28.8 g/mol, and that its density is 0.97 g/L, how many molecules of air do you take in with each breath?# (a) (b) (c) (d) (e)

2.0 x 1022 2.2 x 1022 5.8 x 1022 1.7 x 1022 1.8 x 1022

3. Hydroxylamine nitrate contains 29.17 mass % N, 4.20 mass % H, and 66.63 mass % O. If its molar mass is between 94 and 98 g/mol, what is its molecular formula?# (a) (b) (c) (d) (e)

NH2O5 N2H4O4 N3H3O3 N4H8O2 N2H2O4

4. Balance the following equation:

___Ca3(PO4)2(s) + ___SiO2(s) + ___C(s) → ___CaSiO3(s) + ___CO(g) + ___P4(s) (a) (b) (c) (d) (e)

1:3:8 → 3:8:1 1:3:14 → 3:14:1 1:3:8 → 3:8:2 2:6:10 → 6:10:1 2:6:10 → 6:10:4

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Chem 200 Summer 2016

Final - B

August 16, 2016

5. Aluminum reacts with oxygen to produce aluminum oxide which can be used as an adsorbent, desiccant or catalyst for organic reactions. " 4Al(s) + 3O2(g) → 2Al2O3(s) " A mixture of 82.49 g of aluminum and 117.65 g of oxygen is allowed to react. Identify the limiting reactant and determine the mass of the excess reactant present in the vessel when the reaction is complete.# (a) (b) (c) (d) (e)

Oxygen is the limiting reactant; 19.81 g of aluminum remain. Oxygen is the limiting reactant; 35.16 g of aluminum remain. Aluminum is the limiting reactant; 16.70 g of oxygen remain. Aluminum is the limiting reactant; 35.16 g of oxygen remain. Aluminum is the limiting reactant; 44.27 g of oxygen remain.

6. Lithium forms compounds which are used in dry cells and storage batteries and in hightemperature lubricants. It has two naturally occurring isotopes, 6Li (isotopic mass = 6.015121 amu) and 7Li (isotopic mass = 7.016003 amu). Lithium has an atomic mass of 6.9409 amu. What is the percent abundance of lithium-6?# (a) (b) (c) (d) (e)

92.50% 86.66% 46.16% 7.504% 6.080%

7. The substance, CoCl2, is useful as a humidity indicator because it changes from pale blue to pink as it gains water from moist air. What is its name?# (a) (b) (c) (d) (e)

cobalt dichloride cobalt (II) chloride cobalt chloride cobaltic chloride copper (II) chloride

8. Ammonium sulfate is a fertilizer widely used as a source of nitrogen. Calculate its molecular mass. (a) (b) (c) (d) (e)

63.07 amu 114.10 amu 118.10 amu 128.11 amu 132.15 amu

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Final - B

August 16, 2016

9. Select the precipitate that forms when the following reactants are mixed." Mg(CH3COO)2(aq) + LiOH(aq) #→ (a) (b) (c) (d) (e)

LiCH3COO Li(CH3COO)2 MgOH Mg(OH)2 CH3OH

10. A 0.00100 mol sample of Ca(OH)2 requires 25.00 mL of aqueous HCl for neutralization according to the reaction below. What is the concentration of the HCl?" Ca(OH)2(s) + 2HCl(aq) #→ CaCl2(aq) + H2O(l)# (a) (b) (c) (d) (e)

0.0200 M 0.0400 M 0.0800 M 4.00 x 10¯5 M 8.00 x 10¯5 M

11. Calculate the rms speed of carbon dioxide molecules at STP. (a) (b) (c) (d) (e)

12.4 m/s 155 m/s 393 m/s 260 m/s 4.4 x 104 m/s

12. A system that does no work but which transfers heat to the surroundings has:# (a) (b) (c) (d) (e)

q < 0, E > 0 q < 0, E < 0 q > 0, E > 0 q > 0, E < 0 q < 0, E = 0

13. A system expands from a volume of 1.00 L to 2.00 L against a constant external pressure of 1.00 atm. The work (w) done by the system, is:#Note: 1 atm•L = 101.3 J (a) (b) (c) (d) (e)

-1.00 J -2.00 J -1.01 x 102 J -1.01 x 105 J -1.01 x 107 J

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Chem 200 Summer 2016

Final - B

August 16, 2016

14. A sample container of carbon monoxide occupies a volume of 435 mL at a pressure of 785 torr and a temperature of 298 K. What would its temperature be if the volume were changed to 217.5 mL at a pressure of 785 torr?# (a) (b) (c) (d) (e)

149 K 298 K 387 K 489 K 538 K

15. Select the gas with the highest average kinetic energy per mole at 298 K.# (a) (b) (c) (d) (e)

O2 CO2 H2O H2 All have the same average kinetic energy.

16. The Starship Enterprise is caught in a time warp and Spock is forced to use the primitive techniques of the 20th century to determine the specific heat capacity of an unknown mineral. The 307-g sample was heated to 98.7 ºC and placed into a calorimeter containing 72.4 g of water at 23.6 ºC. The heat capacity of the calorimeter was 15.7 J/K. The final temperature in the calorimeter was 32.4 ºC. What is the specific heat capacity of the mineral?# (a) (b) (c) (d) (e)

0.124 J/(g · K) 0.128 J/(g · K) 0.132 J/(g · K) 0.145 J/(g · K) 0.154 J/(g · K)

17. Calcium hydroxide, which reacts with carbon dioxide to form calcium carbonate, was used by the ancient Romans as mortar in stone structures. The reaction for this process is: " Ca(OH)2(s) + CO2(g) → CaCO3(s) + H2O(g), ΔH = -69.1 kJ" What is the enthalpy change if 3.8 mol of calcium carbonate is formed?# (a) (b) (c) (d) (e)

-18 kJ -69 kJ -73 kJ -260 kJ -270 kJ

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Final - B

August 16, 2016

18. Identify the element of Period 2 which has the following successive ionization energies, in kJ/mol. IE1

IE2

IE3

IE4

IE5

IE6

IE7

IE8

1314

3,389

5,298

7,471

10,992

13,329

71,345

84,087

(a) (b) (c) (d) (e)

Li B O F Ne

19. Arrange the following bonds in order of increasing bond strength.# (a) (b) (c) (d) (e)

C—I < C—Br < C—Cl < C—F C—F < C—Cl < C—Br < C—I C—Br < C—I < C—Cl < C—F C—I < C—Br < C—F< C—Cl C—F < C—Br < C—I < C—Cl

20. In the following Lewis structure for ClO3F, chlorine has a formal charge of ____ and an oxidation number of ____. (a) (b) (c) (d) (e)

7, 7 7, -1 1, 1 1, -1 1, 7

21. Calculate the lattice energy of magnesium sulfide from the data given below. " Mg(s) → Mg(g) ∆H = 148 kJ/mol " Mg(g) → Mg2+(g) + 2e¯ ∆H = 2186 kJ/mol" S8(s) → 8S(g) ∆H = 2232 kJ/mol" S(g) + 2e¯ → S2¯(g) ∆H = 450 kJ/mol" 8Mg(s) + S8(s) → 8MgS(s) ∆H = -2744 kJ/mol" " Mg2+(g) + S2¯(g) → MgS(s) ∆Hlattice = ?# (a) (b) (c) (d) (e)

-3406 kJ/mol -2720. kJ/mol 2720. kJ/mol -2552 kJ/mol -2367 kJ/mol

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August 16, 2016

22. Acetone can be easily converted to isopropyl alcohol by addition of hydrogen to the carbonoxygen double bond. Calculate the enthalpy of reaction using the bond energies given.

"

Bond:

C=O

H—H

H—O

C—H

C—C

C—O

Bond Energy (kJ/mol):

745

436

464

414

347

351

(a) (b) (c) (d) (e)

-484 kJ -366 kJ -48 kJ +48 kJ +366 kJ

23. What is the frequency of a photon absorbed when the hydrogen atom undergoes a transition from n1=2 and n2=4. (a) (b) (c) (d) (e)

4.86 x 10-7 Hz 4.09 x 10-19 Hz 4.67 x 10-6 Hz 6.42 x 107 Hz 6.17 x 1014 Hz

24. In the ground state of an atom of silver (Ag), how many electrons will there be with the quantum number l = 1? (a) (b) (c) (d) (e)

9 12 18 24 36

25. In which one of the following species is the central atom (the first atom in the formula) likely to violate the octet rule? (a) (b) (c) (d) (e)

AlF4¯ XeO3 SiCl4 NH3 CH2Cl2

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Chem 200 Summer 2016

Final - B

August 16, 2016

26. What is the molecular shape of NO2¯ as predicted by the VSEPR theory?# (a) linear (b) trigonal planar (c) bent (d) tetrahedral (e) trigonal bipyramidal 27. Which of the following should have the smallest surface tension at a given temperature?# (a) (b) (c) (d) (e)

CH4 CF4 CCl4 CBr4 CI4

28. The two most abundant intermolecular forces in DNA structure are: (a) (b) (c) (d) (e)

dipole-dipole forces. London dispersion forces. hydrogen bonding. ion-dipole interactions. ionic bonds.

29. Valence bond theory predicts that carbon will use _____ hybrid orbitals in the carbonate anion, CO32¯.# (a) (b) (c) (d) (e)

sp sp2 sp3 sp3d sp3d2

30. The nitrosonium ion, NO+, forms a number of interesting complexes with nickel, cobalt, and iron. According to molecular orbital theory, which of the following statements about NO+ is correct?#Use the MO diagram provided in on page 13. (a) (b) (c) (d) (e)

NO+ has a bond order of 2 and is paramagnetic. NO+ has a bond order of 2 and is diamagnetic. NO+ has a bond order of 3 and is paramagnetic. NO+ has a bond order of 3 and is diamagnetic. NO+ has a bond order of 1 and is diamagnetic.

31. The Clausius-Clapeyron equation is used in calculations of# (a) (b) (c) (d) (e)

melting and freezing points. vapor pressures of liquids osmotic pressures of solutions. heats of vaporization at different temperatures. crystal structure.

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Chem 200 Summer 2016

Final - B

August 16, 2016

32. Determine the freezing point of a solution which contains 0.31 mol of sucrose in 175 g of water. Kf = 1.86 ºC/m# (a) (b) (c) (d) (e)

3.3 ºC 1.1 ºC 0.0 ºC -1.1 ºC -3.3 ºC

33. Iridium has the highest density of any element. It crystallizes in the face-centered cubic lattice with a unit cell edge length of 283.9 pm. Calculate the density of an iridium crystal. The packing efficiency for FCC is 74%. Note: Vsphere= (4/3)·π·r3 and π = 3.14 (a) (b) (c) (d) (e)

55.76 g/cm3 30.49 g/cm3 22.56 g/cm3 10.56 g/cm3 9.457 g/cm3

34. Which of the following ions will be expected to have the most negative heat of hydration, ∆Hhydr?# (a) (b) (c) (d) (e)

Na+ Cs+ Ca+2 FI-

35. Sodium hydroxide is a common ingredient in drain cleaners such as Drano. The mole fraction of sodium hydroxide in a saturated aqueous solution is 0.310. What is the molality of the solution?# (a) (b) (c) (d) (e)

0.310 m 0.690 m 1.24 m 11.2 m 24.9 m

36. Which of the following aqueous solutions will have the lowest osmotic pressure?# (a) (b) (c) (d) (e)

0.10 m KOH 0.10 m RbCl 0.05 m CaSO4 0.05 m BaCl2 0.10 m K2SO4

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Final - B

August 16, 2016

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Soluble Ionic Compounds Solubility Rules:

Exceptions: Li+,

Na+,

All compounds of Group 1A (1) ions K+, etc, and ammonium ion NH4+ are soluble All common nitrates (NO3-) are soluble All common acetates (CH3COO-) are soluble Most perchlorates (ClO4-) are soluble All common chlorides (Cl-) are soluble All common bromides (Br-) are soluble All common iodides (I-) are soluble

Ag+, Pb2+, Cu+, Hg22+

All common sulfates (SO42-) are soluble

Ca2+, Sr2+, Ba2+, Ag+, Pb2+

Insoluble Ionic Compounds Insolubility Rules: All common metal hydroxides insoluble

Exceptions: (OH-)

are

Group 1A (1) ions - Li+, Na+, K+, etc The larger Group 2A (2) ions beginning with Ca2+

All common carbonates (CO32-) are insoluble All common phosphates (PO43-) are insoluble

Group 1A (1) ions NH4+ ammonium ion

All common sulfides (S2-) are insoluble

Group 1A (1) ions Group 2A (2) ions NH4+ ammonium ion

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