Chemistry 121 Fall 2009 Oregon State University Final Exam December 7, 2009 Dr. 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 test form number (listed above), 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 40 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 and note card in the appropriate stacks. You may keep the exam packet, so please show your work and mark the answers you selected on it. centi (c) = 1/100 milli (m) = 1/000 kilo (k) = 1000 micro (μ) = 10-6 nano (n) = 10-9 1 mole = 6.022 x 1023 1 inch = 2.54 cm (exact) 1 kg = 2.2 pounds 1 foot = 12 inches (exact) K = 273.15 + °C 1 atm = 760 mm Hg = 760 Torr - - - Hydroxide OH Cyanide CN Nitrate NO3 - 2- 3- Acetate CH3COO Carbonate CO3 Phosphate PO4 + + 2- Hydronium H3O Ammonium NH4 Sulfate SO4 Abbreviated Solubility Rules: Rule 1:All nitrates, group 1A metal salts and ammonium salts are soluble. Rule 2: All carbonates, hydroxides, phosphates and sulfides are insoluble. Rule 3: Rule 1 always takes precedent.
M1V1 = M2V2 MacidVacid = MbaseVbase PV P V 1 1 2 2 n1T1 n2T2 L atm 3RT kg m 2 R = 0.0821 R = 8.314 mol K rms Molar Mass s 2 mol K PV = nRT q = mcΔT q = mΔH -18 8 E = q + w RH = 2.180 x 10 J/photon c = 3.00 x 10 m/s h = 6.626 x 10-34 J·s c E = hν h mv
Unit 1 (Material Assessed on Exam 1)
1. A student measures a rectangular piece of filter paper to be 132.45 cm by 83.29 cm. The area of the filter paper (with the proper number of significant figures) is:
(A) 1.103176 x 104 cm2 (B) 1.10318 x 104 cm2 (C) 1.1032 x 104 cm2 (D) 1.103 x 104 cm2 (E) 1.10 x 104 cm2
2. Which of the following statements is incorrect?
(A) The formula of lithium carbonate is Li2CO3 (B) The name of SF6 is sulfur hexafluoride (C) The molecular mass of Al2(SO4)3 is 342.14 g/mol (D) 12C, 13C, and 14C have 6, 7, and 8 protons, respectively (E) One mole of krypton atoms has a mass of 83.80 grams
3. The mass percent composition of CaSO4 is:
(A) 16.7% Ca 16.7% S 66.7% O (B) 20.0% Ca 20.0% S 60.0% O (C) 25.1% Ca 20.5% S 54.4% O (D) 29.4% Ca 23.6% S 47.0% O (E) 33.3% Ca 33.3 % S 33.3% O
4. Which of the following pairs are isotopes?
(A) 16N and 16O (B) 40Ar and 20Ne (C) 14N and 16N (D) 20F− and 20Ne (E) 15N and 15O 5. Which of the following chemical formulae is incorrect?
(A) BeO (B) Mg(NO3)2 (C) LiOH (D) Ba2(PO4)3 (E) (NH4)2S
6. The formula of iron (III) carbonate is:
(A) IrCO3 (B) FeCO3 (C) Fe3CO3 (D) Fe3(CO3)2 (E) Fe2(CO3)3
7. When the equation: C9H20 + O2 → CO2 + H2O is correctly balanced,
(A) 10 moles of O2 are consumed (B) 12 moles of O2 are consumed (C) 14 moles of O2 are consumed (D) 16 moles of O2 are consumed (E) 18 moles of O2 are consumed
8. A student obtains 192.51 grams of methane, CH4. How many hydrogen atoms are present?
(A) 1.993 x 1023 hydrogen atoms (B) 3.613 x 1025 hydrogen atoms (C) 2.891 x 1025 hydrogen atoms (D) 7.226 x 1024 hydrogen atoms (E) 12 hydrogen atoms 9. 238U has:
(A) 238 protons, 119 neutrons, 119 electrons (B) 119 protons, 119 neutrons, 119 electrons (C) 92 protons, 146 neutrons, 119 electrons (D) 92 protons, 92 neutrons, 119 electrons (E) 92 protons, 146 neutrons, 92 electrons
10. Which of the following statements is false?
(A) Electrons are located outside of the nucleus (B) Protons and neutrons have similar masses (C) Electrons carry a negative charge; protons carry a positive charge (D) A neutral atom has an equal number of protons and electrons (E) Electrons are roughly 2000 times as massive as protons and neutrons; therefore, most of the mass in an atom is located outside the nucleus
11. A fictitious element, Rihannaium, has two naturally occurring isotopes. 285Ri has a mass of 284.67 g/mol and is 28.7557% abundant. 288Ri has a mass of 287.73 g/mol and is 71.2443% abundant. What is the average atomic mass of Rihannaium?
(A) 285.96 g/mol (B) 287.96 g/mol (C) 286.96 g/mol (D) 286.85 g/mol (E) 286.20 g/mol 12. How many grams of O2 (g) are required to react completely with 743.37 grams of P4 (s) to produce P4O10 (s)?
P4 (s) + 5 O2 (g) P4O10 (s)
(A) 3716.9 grams of O2 (g) are required (B) 159.99 grams of O2 (g) are required (C) 191.99 grams of O2 (g) are required (D) 959.96 grams of O2 (g) are required (E) 30.000 grams of O2 (g) are required
13. There are 6.344 x 1023 sildenafil molecules in 500.0 g of sildenafil. What is the molar mass of sildenafil?
(A) 140.7 g/mol (B) 474.6 g/mol (C) 281.4 g/mol (D) 97.54 g/mol (E) The answer cannot be calculated without the molecular formula of sildenafil. Unit 2 (Material Assessed on Exam 2)
14. The density of an unknown gas is measured to be 5.37 g/L at 298 K and 1.00 atm. What is the unknown gas?
(A) He (g) (B) Ne (g) (C) Ar (g) (D) Kr (g) (E) Xe (g)
15. A student obtains a 6.00 liter balloon at 22.6 ºC and 752 mm Hg. The student cools the balloon to -92.1 ºC. The volume of the balloon at -92.1 ºC is:
(A) 3.67 L (B) 1.47 L (C) 2.95 L (D) 0.340 L (E) 0.273 L
16. The root-mean-square speed of Cl2 (g) at 1.20 atm and 350 K is:
(A) 34.9 m/s (B) 123 m/s (C) 351 m/s (D) 1.23 x 106 m/s (E) 11.1 m/s 17. A student combusts 344.7 grams of hexane (C6H14) in excess oxygen gas to produce carbon dioxide gas and water at 739.4 mm Hg and 299 K. How many liters of carbon dioxide are produced?
C6H14 (g) + 19/2 O2 (g) 6 CO2 (g) + 7 H2O (g)
(A) 22.40 L CO2 are produced (B) 24.40 L of H2O are produced (C) 100.9 L of H2O are produced (D) 605.6 L CO2 are produced (E) 36.00 L of H2O are produced
18. A sample of Cl2 (g) is observed to effuse through a porous barrier in 0.855 minutes. Under the same conditions, the same number of moles of an unknown gas requires 0.574 minutes to effuse through the same barrier. Which of the following is the unknown gas?
(A) O2 (g) (B) N2 (g) (C) Cl2 (g) (D) H2 (g) (E) Xe (g)
19. Which of the following equations is exothermic?
(A) H2O(l) H2O(g) (B) CO2(s) CO2(g) (C) H2O(s) H2O(l) (D) CH4(g) + 2 O2(g) CO2(g) + 2 H2O(g) 20. Determine ΔH˚reaction for the following reaction:
2 CH4 (g) + O2 (g) → 2 CH3OH (g)
(A) -126.4 kJ (B) -552.0 kJ (C) -276.0 kJ (D) -252.8 kJ (E) +126.4 kJ
21. Determine ΔH° for the reaction: 4 PCl5 (g) → P4 (s) + 10 Cl2 (g)
Given: 2 P4 (s) + 12 Cl2 (g) → 8 PCl3 (g) H° = -5420 kJ
PCl5 (g) → PCl3 (g) + Cl2 (g) H° = +277 kJ
(A) + 5697 kJ (B) + 3818 kJ (C) - 5143 kJ (D) - 4312 kJ (E) +19.6 kJ
22. How much heat is required to raise the temperature of 600 grams of steam, H2O (g), from 120 C to 159 C?
(A) 53.8 kJ (B) 32.3 kJ (C) 53,820 kJ (D) 23.4 kJ (E) 97,812 kJ 23. 75 kJ of heat will cause a 300.0 gram sample of water, H2O (l), to increase from 20.0 ºC to:
(A) 72.4 ºC (B) 25.0 ºC (C) 1125 ºC (D) 94.1 ºC (E) 79.8 ºC
24. A student mixes two solutions: Li3PO4 (aq) and Sr(NO3)2 (aq). The solid precipitate formed is:
(A) LiNO3 (s) (B) Sr3(PO4)2 (s) (C) LiOH (s) (D) SrO (s) (E) Li3PO4 (s)
25. Consider the combustion of magnesium, 2 Mg (s) + O2 (g) 2 MgO (s) H° = – 1203 kJ. How much heat is released when a student combusts 340.3 g of Mg (s)?
(A) 1203 kJ (B) 2406 kJ (C) 8422 kJ (D) 16,843 kJ (E) 4812 kJ Unit 3 (Material Discussed after Exam 2)
26. A student ( ) reads the label on the back of a microwave oven as sees the frequency is listed as 2.45 gigahertz (2.45 x 109 hertz). What is the wavelength of these waves? [1 m = 100 cm]
(A) 2.45 cm (B) 2.45 x 1011 cm (C) 12.2 cm (D) 8.17 cm (E) 4.92 x 10-9 cm
27. Consider the electromagnetic spectrum. Which of the following statements is false?
(A) X-Rays travel faster in a vacuum than red light in a vacuum (B) Blue light is greater in energy than red light (C) Yellow light has a lower frequency than ultraviolet (D) Yellow light has a lower frequency than green light (E) Radio waves have longer wavelengths than red light
28. The energy of one mole of blue photons is 249 kJ. What is the wavelength of this blue light?
(A) 450 nm (B) 460 nm (C) 470 nm (D) 480 nm (E) 490 nm 29. The wavelength of the wave shown below is approximately:
(A) 0.5 cm (B) 1 cm (C) 2 cm (D) 4 cm (E) 8 cm
30. The frequency of red laser photons having a wavelength of 630 nm is:
1 (A) 1.60 x 10-9 s 1 (B) 1.60 x 109 s 1 (C) 4.76 x 1014 s 1 (D) 2.10 x 1014 s 1 (E) 8.91 x 1014 s
31. Consider the Bohr Model for the Hydrogen Atom. Which of the following electron transitions releases the most energy—please draw a picture as an aid?
(A) n = 7 to n = 6 (B) n = 7 to n = 5 (C) n = 3 to n = 2 (D) n = 3 to n = 1 (E) n = 2 to n = 1 32. Consider the Bohr Model for the Hydrogen Atom. Which of the following electron transitions releases electromagnetic radiation with the shortest wavelength—please draw a picture as an aid?
(A) n = 2 to n = 1 (B) n = 3 to n = 2 (C) n = 4 to n = 3 (D) n = 5 to n = 4 (E) n = 6 to n = 5
33. Which of the following sets of quantum numbers is not valid?
(A) n = 1, l = 0, ml = 0, ms = +½ (B) n = 3, l = 0, ml = 0, ms = +½ (C) n = 3, l = 2, ml = 0, ms = +½ (D) n = 2, l = 2, ml = 0, ms = +½ (E) n = 2, l = 1, ml = -1, ms = +½
34. Which set of four quantum numbers describes an electron in the orbital pictured below?
(A) n = 1, l = 0, ml = 0, ms = +½ (B) n = 2, l = 0, ml = 0, ms = +½ (C) n = 2, l = 1, ml = 0, ms = +½ (D) n = 3, l = 1, ml = 0, ms = +½ (E) n = 3, l = 2, ml = 0, ms = +½ 35. deBroglie’s proposition regarding the nature of matter was:
(A) All matter travels at the same speed (B) All photons are in the visible region of the electromagnetic spectrum (C) The frequency of electromagnetic radiation is inversely proportional to the energy (D) All matter in motion exhibits a wavelength (E) You will truly be happy and free when you rid yourself of your matter
36. Consider an electron (mass of 9.10939x10-31 kg) traveling at 1/20th the speed of light. Which of the following statements is correct?
(A) The wavelength of the e- is 4.85 x 10-11 m and this has practical significance (B) The wavelength of the e- is 530 nm and this does not have practical significance (C) The wavelength of the e- is 3.89 x 10-10 m and this has practical significance (D) The wavelength of the e- is 4.20 x 10-11 m and this has practical significance (E) The wavelength of the e- is 4.20 x 10-11 m and this does not have practical significance
37. [True or False?] A ground-state lithium atom has a single electron in the 2s orbital.
(A) True (B) False 38. The ground-state electron configuration of a nitrogen atom is:
(A) 1s22s23s23p1 (B) 1s22s23s1 (C) 1s22s22p5 (D) 1s22s22p3 (E) 1s22s23s3
39. The ground-state electron configuration of a fluoride ion (F-) is:
(A) 1s22s23s23p2 (B) 1s22s23s1 (C) 1s22s22p6 (D) 1s22s22p63s23p2 (E) 1s22s22p4 40. Because of CH 121...
(A) My heart is chock-full of love
(B) I have saved over 20% on my car insurance
(C) I have learned how to force my way through the rear window of an SUV with a 9-iron should it ever become necessary to pull my spouse from danger
(D) I have learned that after pulling my spouse from safety there is a second non-traditional use for a 9-iron
(E) I have spent endless hours in Gilbert Hall downloading apps for my iPhone
Questions 1 through 40 each have 4 points attached. Any response to Question 40 will receive full credit (4 Points); even no response.
The point total for this exam is 160 points. See the grade sheet or CH 121 web syllabus for grade computation details.
Final exam keys, scores, and course grades will be posted on the CH 121 website as they become available.
Have an excellent and safe Winter Break ☺