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Note: This document is not a complete practice exam. Rather, it is a compilation of questions from the 2013 AP Chemistry International Exam that support the learning objectives of the redesigned AP course. Questions that do not support this course have been removed. This publication may be used to help students prepare for the 2014 AP Chemistry exam and future exams. Following the last page of the exam, there is an answer key as well as the learning objectives which are supported by each of the questions herein. This Practice Exam from the 2013 international administration is provided by the College Board for AP Exam preparation. Teachers are permitted to download the materials and make copies to use with their students in a classroom setting only. To maintain the security of this exam, teachers should collect all materials after their administration and keep them in a secure location. Exams may not be posted on school or personal websites, nor electronically redistributed for any reason. Further distribution of these materials outside of the secure College Board site disadvantages teachers who rely on uncirculated questions for classroom testing. Any additional distribution is in violation of the College Board ’s copyright policies and may result in the termination of Practice Exam access for your school as well as the removal of access to other online services such as the AP Teacher Community and Online Score Reports. AP Chemistry: Sample items from the 2013 administration
769272 AP ® Chemistry Exam Monday morning, May 6, 2013 SECTION I: Multiple Choice 2013 I affirm that: This exam is being administered onMonday morning,May 6,2013,and will begin between the hours of 8 a .m .and9a .m .* If this exam is being offered to me at any other time or any other date ,I will refuse to take the exam and will contact the Office of Testing Integrity . I will not take this exam booklet from the room or disclose any of the multiple - choice questions to anyone ,including my AP teacher . I understand and accept that my exam score may be canceled if I do not meet these conditions and sign below . *The administration of this exam in Alaska must begin between 7 a .m .and8a .m . Signature Date Print your full legal name here: (First) (M.I.)(Last) ©2013 The College Board. College Board, Advanced Placement Program, AP, and the acorn logo are registered trademarks of the College Board. Unauthorized reproduction or use of any part of this test is prohibited and may result in cancellation of scores and possible prosecution to the fullest extent of the law. TEST BOOK SERIAL NUMBER AP EXAM LABEL Form I Form Code 4JBP4-S 25 M25IXX1
At a Glance Total Time1 hour, 30 minutes Number of Questions75 Percent of Total Score50% Writing InstrumentPencil required Electronic DeviceNone allowed Instructions Section I of this exam contains 75 multiple-choice questions.Fill in only the circles for numbers 1 through 75 of the answer sheet. Indicate all of your answers to the multiple- choice questions on the answer sheet.No credit will be given for anything written in this exam booklet, but you may use the booklet for notes or scratch work. After you have decided which of the suggested answers is best, completely fill in the corresponding circle on the answer sheet. Give only one answer to each question. If you change an answer, be sure that the previous mark is erased completely. Here is a sample question and answer. Use your time effectively, working as quickly as you can without losing accuracy. Do not spend too much time on any one question. Go on to other questions and come back to the ones you have not answered if you have time. It is not expected that everyone will know the answers to all of the multiple- choice questions. Your total score on the multiple- choice section is based only on the number of questions answered correctly. Points are not deducted for incorrect answers or unanswered questions. DO NOT OPEN THIS BOOKLET UNTIL YOU ARE TOLD TO DO SO. AP ® Chemistry Exam SECTION I: Multiple Choice 2013 Form I Form Code 4JBP4-S 25
GO ON TO THE NEXT PAGE. -2- MATERIAL IN THE FOLLOWING TABLE MAY BE US EFUL IN ANSWERING THE QUESTIONS IN THIS SECTION OF THE EXAMINATION.
Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -3- CHEMISTRY Section I Time — 1 hour and 30 minutes NO CALCULATOR MAY BE USED WITH SECTION I. Note: For all questions, assume that the temperature is 298 K, the pressure is 1.00 atmosphere, and solutions are aqueous unless otherwise specified. Throughout the test the following symbols have th e definitions specified unless otherwise noted. T = temperature L, mL = liter(s), milliliter(s) P = pressure g = gram(s) V = volume nm = nanometer(s) S = entropy atm = atmosphere(s) H = enthalpy mm Hg = millimeters of mercury G = Gibbs free energy J, kJ = joule(s), kilojoule(s) R = molar gas constant V = volt(s) n = number of moles mol = mole(s) M = molar m = molal Part A Directions: Each set of lettered choices below refers to the numbered statements immediately following it. Select the one lettered choice that best fits each statement and then fill in the corresponding circle on the answer sheet. A choice may be used once, more than once, or not at all in each set. Question 1 refer to the following compounds at 25 ∞C and 1.0 atm. (A) CO 2 (B) PbO 2 (C) CaO (D) N 2O5 (E) Cu 2O 1. Contains an element in a +1 oxidation state Questions 4-7 refer to the following species. (A) H 2O (B) NH 3 (C) BH 3 (D) CH 4 (E) SiH 4 4. Has two lone pairs of electrons 5. Has a central atom with less than an octet of electrons 6. Is predicted to have the largest bond angle 7. Has a trigonal-pyramidal molecular geometry Questions #2 & 3 did not align with the new course and have been removed.
Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -4- Questions 8-9 refer to the chemical reactions represented below. (A) 2 C 6H6( l ) + 15 O 2(g ) Æ 12 CO 2(g ) + 6 H 2O(l ) (B) C 2H3O2 -( aq) + H 3O+(aq) Æ HC 2H3O2(aq) + H 2O( l) (C) 4 H +( aq) + 4 Co 2+(aq) + O 2(g ) + 24 NH 3(aq) Æ 4 Co(NH 3)63+ ( aq) + 2 H 2O(l ) (D) CaCO 3( s) Æ CaO( s) + CO 2(g ) (E) 2 H 2O2( l ) Æ O 2(g ) + 2 H 2O(l ) 8. The reaction between a Brønsted- Lowry acid and a Brønsted-Lowry base 9. The reaction in which a single species is both oxidized and reduced Questions #10 - 14 did not align with the new course and have been removed.
Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -5- Questions 15-17 refer to the 1 L flasks shown below. 15. In which flask do th e molecules have the greatest average spe ed ? 16. Which flask contains the smallest number of moles of gas? 17. Which flask contains the sample with the greatest density?
Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -6- Part B Directions: Each of the questions or inco mplete statements below is followe d by five suggested answers or completions. Select the one that is best in each case and then fill in the corresponding circle on the answer sheet. 18. Which of the following elements has the largest first ionization energy? (A) Li (B) Be (C) B (D) C (E) N 19. A 0.20 mol sample of MgCl 2( s) and a 0.10 mol sample of KCl( s) are dissolved in water and diluted to 500 mL. What is the concentration of Cl - in the solution? (A) 0.15 M (B) 0.30 M (C) 0.50 M (D) 0.60 M (E) 1.0 M 20. Atoms of Mg combine with atoms of F to form a compound. Atoms of which of the foll owing elem ents combine with atoms of F in the same ratio? (A) Li (B) Ba (C) Al (D) Cl (E) Ne C3H8( g ) + 5 O 2(g ) Æ 3 CO 2(g ) + 4 H 2O(l ) 21. In the reaction represented above, what is the total number of moles of reactants consu m ed when 1.00 m ole of CO 2( g ) is produced ? (A) 0.33 mol (B) 1.33 mol (C) 1.50 mol (D) 2.00 mol (E) 6.00 mol 22. How many protons, neutro ns, and electrons are in an 56 26Fe atom? Protons Neutrons Electrons (A) 26 30 26 (B) 26 56 26 (C) 30 26 30 (D) 56 26 26 (E) 56 82 56 23. Which of the following is th e electron configuration of an excited atom that is likely to emit a quantum of energy? (A) 1 s 2 2s 22p 6 3 s 23p 1 (B) 1 s 2 2s 22p 6 3 s 23p 5 (C) 1 s 2 2s 22p 6 3 s 2 (D) 1 s 2 2s 22p 6 3 s 1 (E) 1 s 2 2s 22p 6 3 s 13p 1 24. Which of the following mo lecules contains polar covalent bon ds but is a no npolar molecule? (A) CH 3Cl (B) CH 2Cl 2 (C) NH 3 (D) CCl 4 (E) N 2 H2 + F 2 Æ 2 HF 25. In the reaction represented above, what mass of HF is produced by the reaction of 3.0 × 10 23 molecules of H 2 with excess F 2 ? (Assume the reaction goes to completion.) (A) 1.0 g (B) 4.0 g (C) 10. g (D) 20. g (E) 40. g
Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -7- 26. For which of the following reaction mixtures at equilibrium would reducing the volume of the container at constant temperature cause the equilibrium to shift toward the products? (A) SrCO 3(s) Æ ¨ SrO(s) + CO 2( g ) (B) C(s) + CO 2( g ) Æ ¨ 2 CO( g) (C) CO(g ) + H 2O(g) Æ ¨ CO 2( g ) + H 2(g ) (D) PCl 5( g ) Æ ¨ PCl 3( g ) + Cl 2(g ) (E) 2 NO 2( g ) Æ ¨ N 2O4( g ) 28. A 2 L sample of N 2( g ) and a 1 L sample of Ar( g), each originally at 1 atm and 0 °C, are combined in a 1 L tank. If the temperature is held constant, what is the total pressure of the gases in the tank? (A) 1 atm (B) 2 atm (C) 3 atm (D) 4 atm (E) 5 atm 29. Which of the following processes involves the greatest increase in entropy? (A) SO 3(g ) + H 2(g ) Æ SO 2(g ) + H 2O(g ) (B) N 2(g) + 3 H 2( g ) Æ 2 NH 3(g ) (C) Ag +( aq) + Cl -( aq) Æ AgCl( s) (D) C 2H2( g ) + 2 H 2(g ) Æ C 2H6(g ) (E) MgSO 3( s) Æ MgO(s) + SO 2(g ) N 2O5( g ) Æ ¨ 2 NO 2( g ) + 1 QnQ(g ) 30. The equilibrium constant for the gas phase reaction above is 95 at 25 ∞C. What is the value of the equilibrium constant fo r the following reaction at 25∞C? O 2(g ) + 4 NO 2(g ) Æ ¨ 2 N 2O5( g ) (A) (95) 2 (B) 95 (C) 1 2 (95) (D) 1 95 (E) 2 1 (95) C2H4( g ) + H 2(g ) platinum æ æææ Æ C 2H6(g ) 32. C 2H4( g ) is reduced by H2(g ) in the presence of a solid platinum catalyst, as represented by the equation above. Factors that could affect the rate of the reaction include which of the following? I. Changes in the partial pressure of H2(g ) II. Changes in the particle size of the platinum catalyst III. Changes in the temperature of the reaction system (A) III only (B) I and II only (C) I and III only (D) II and III only (E) I, II, and III Question # 31 doesn not align with the new course and has been removed. Question #27 did not align with the new course and has been removed.
Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -8- 33. For an experiment, a student needs 100.0 mL of 0.4220 M NaCl. If the student starts with NaCl( s) and distilled water, which of the following pieces of laboratory glassware should the student use to prepare the solution with the greatest accuracy? (A) 25 mL volumetric pipet (B) 100 mL Erlenmeyer flask (C) 100 mL graduated cylinder (D) 100 mL volumetric flask (E) 1 L beaker Questions # 34-36 did not align with the new course and h ave been removed.
Unauthorized copying or reuse of any part of this page is illegal. GO ON s O THE NEXT PAGE. -9- 2 NH 3( g ) → 3 H 2(g ) + N 2(g ) 298H DD = 92 kJ/mol rxn 37. According to the information above, what is the standard enthalpy of formation, fH DD, for NH 3( g ) at 298 K ? (A) −92 kJ/mol (B) − 46 kJ/mol (C) 46 kJ/mol (D) 92 kJ/mol (E) 184 kJ/mol 38. The percentage of silver in a solid sample is determined gravimetrically by converting the silver to Ag +( aq) and precipitating it as silver chloride. Failure to do which of the following could cause errors in the analysis? I. Account for the mass of the weighing paper when determining the mass of the sample II. Measure the temperature during the precipitation reaction III. Wash the precipitate IV. Heat the AgCl precipitate to constant mass (A) I only (B) I and II (C) I and IV (D) II and III (E) I, III, and IV Question #39 did not align with the new course and has been removed.
Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -10- HSO 4 -( aq) + CO 3 2 - (aq) Æ ¨ SO 4 2 - (aq) + HCO 3 -( aq ) 40. The reaction represented a bove is observed to pr oceed spontaneousl y to the right in aqueous solution. In this system the strongest base is (A) SO 4 2 - (aq ) (B) CO 3 2 - (aq ) (C) H 2O(l ) (D) HCO 3 -( aq ) (E) HSO 4 -( aq) . . . LiHCO 3( aq) + . . . H 2SO 4(aq) Æ . . . Li 2SO 4(aq) + . . . H 2O(l ) + . . . CO 2(g) 41. When the equation above is balanced and the coefficients are reduced to lowest whole-number terms, what is the coefficient of H 2O(l ) ? (A) 1 (B) 2 (C) 3 (D) 4 (E) 5
Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -11- 42. Which of the following lists the substances F 2 , HCl, and HF in order of i ncreasing boiling po int? (A) HF < HCl < F 2 (B) HF < F 2 < HCl (C) HCl < F 2 < HF (D) HCl < HF < F 2 (E) F 2 < HCl < HF 43. Gases generated in a chemical reaction are some- times collected by the displacement of wa ter, as shown above. Which of the following gases can be quantitatively collected by this method? (A) H 2 (B) CO 2 (C) HCl (D) SO 2 (E) NH 3 44. When a 3.22 g sample of an unknown h ydrate of sodium sul fate, Na 2SO 4 x H 2O( s), is heated, H 2O (molar mass 18 g) is driven off. Th e mass of the anhy drous Na 2SO 4(s) (molar mass 142 g) that remains is 1.42 g. The value of x in the hydrate is (A) 0.01 3 (B) 1.8 (C) 6.0 (D) 10. (E) 20. 45. A 0.10 M solution of a weak monoprotic acid has a pH equal to 4.0. T he ionization constant, K a , of the acid is (A) 1 × 10 - 3 (B) 1 × 10 - 4 (C) 1 × 10 - 7 (D) 1 × 10 - 8 (E) 1 × 10 - 9 46. In an insulated cup of neglig ible heat capacity, 50. g of water at 40. °C is mixed with 30. g of water at 20. °C. The final temper ature of the mixture is closest to (A) 22 ° C (B) 27° C (C) 30. ° C (D) 33 ° C (E) 38° C
Unauthorized copying or reuse of any part of this page is illegal. GO ON s O THE NEXT PAGE. -12- 47. Which of the following is an isomer of CH 3OCH 3 ? (A) CH 3CH 3 (B) CH 3COOH (C) CH 3CH 2OH (D) CH 3CH 2CH 3 (E) CH 3CH 2OCH 2CH 3 48. Potassium hydrogen p hthalate, KHP, is used as a primary standard for determining the concentration of a solution of NaOH by titration. If the KHP has not been dried before weighing, the calculated molarity of the NaOH would be (A) higher than the actual value, since water is included in the apparent mass of KHP (B) higher than the actual value, since the presence of water requires a larger volume of titrant (C) lower than the actual value, since NaOH absorbs water (D) unaffected, since KHP is a strong acid (E) unaffected, since water is routinely added before the titration 49. Which of the following substances has the greatest solubility in C5H12(l) at 1 atm ? (A) SiO 2( s) (B) NaCl(s) (C) H 2O(l ) (D) CCl 4( l) (E) NH 3( g ) Question #50 did not align with the new course and has been removed.
Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -13- Experiment Initial [X ] (mol L - 1) Initial [Y ] (mol L - 1) Initial Rate of Formation of Z (mol L - 1 s- 1) 1 0.10 0.30 4.0 ¥10 - 4 2 0.20 0.60 1.6 ¥10 - 3 3 0.20 0.30 4.0 ¥10 - 4 51. The data in the table above were obtained for the reaction X + Y Æ Z . Which of the following is the rate law for the reaction? (A) Rate = k[X] 2 (B) Rate = k[Y]2 (C) Rate = k[X][ Y ] (D) Rate = k[X] 2[Y] (E) Rate = k[X][ Y]2
Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -14- 2 H 2( g ) + O 2(g ) Æ 2 H 2O(g ) 52. For the reaction represented above at 25 ° C, what are the signs of ΔH°, Δ S°, and ΔG° ? Δ H∞ ΔS∞ ΔG∞ (A) + + + (B) + + - (C) + - - (D) - - - (E) - - + 53. What is the empirical formula of an oxide of chromium that is 48 percent oxy gen by mass? (A) CrO (B) CrO 2 (C) CrO 3 (D) Cr 2O (E) Cr 2O3 54. High solubility of an ioni c solid in water is favor ed by which of t he following conditions? I. The existence of strong ionic attractions in the crystal lattice II. The formation of strong io n-dipole attractions III. An increase in entropy upon dissolving (A) I only (B) I and II only (C) I and III only (D) II and III only (E) I, II, and III 55. Which of the following stat ements is true for the equilibrium vapor pressure of a liqui d in a closed system ? (A) It remains constant when the temperatur e increas es. (B) It decreases to half its original value if the volume of the gas phase is doubled. (C) It increases to twice its original value if the volume of the liquid phase is doubled. (D) It decreases to half its original value if the surface a rea of the liquid is reduced by one-half. (E) It is independent of the volume of the vapor phase.
Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -15- 56. An unknown acid is dissolved in 25 mL of water and titrated with 0.1 00 M NaOH. The results are shown in the ti tration curve above. Which of the following could be the unk nown acid? (A) Fluoroacetic acid, p K a = 2.6 (B) Glycolic acid, p K a = 3.8 (C) Propanoic acid, p K a = 4.9 (D) Hypochloro us acid, p K a = 7.5 (E) Boric acid, p K a = 9.3
Unauthorized copying or reuse of any part of this page is illegal. GO ON s O THE NEXT PAGE. -16- 57. Which of the following lists Mg, P, and Cl in order of increasing atomic radius? (A) Cl < P < Mg (B) Cl < Mg < P (C) Mg < P < Cl (D) Mg < Cl < P (E) P < Cl < Mg Al 3+( aq) + 3 e - Æ Al( s) E∞ = -1.66 V Ag +( aq) + e - Æ Ag( s) E∞ = + 0.80 V 59. According to the standard reduction potentials given above, what is the standard cell potential for the reaction represented below? 3 Ag +(aq) + Al( s) Æ 3 Ag( s) + Al 3+(aq) (A) -1.74 V (B) -0.86 V (C) +1.74 V (D) + 2.46 V (E) + 4.06 V () () ()XY 2 Z gg g + R 60. When 4.00 mol each of ()Xg and ()Yg are placed in a 1.00 L vessel and allowed to react at constant temperature according to the equation above, 6.00 mol of ()Z g is produced. What is the value of the equilibrium constant, cK ? (A) 3 (B) 6 (C) 8 (D) 16 (E) 36 61. If the oxygen isotope 20O has a half-life of 15 seconds, what fraction of a sample of pure 20O remains after 1.0 minute? (A) 1 Q (B) 1 4 (C) 7 30 (D) 1 8 (E) 1 16 Question #58 did not align with the new course and has been removed.
Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -17- X Æ products 62. Pure substance X decomposes according to the equation abo ve. Which of the following graphs indicates that the rate of decomposition i s second order in X ? (A) (B) (C) (D) (E)
Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -18- 2 MnO 4 -( aq) + 5 C 2O4 2 − (aq) + 16 H +(aq) → 2 Mn 2+(aq) + 10 CO 2(g ) + 8 H 2O(l ) 63. Permanganate and oxalate ions react in an acidified solution according to the balanced equation above. How many moles of CO 2( g ) are produced when 20. mL of acidified 0.20 M KMnO 4 solution is added to 50. mL of 0.10 M Na 2C2O4 solution? (A) 0.0040 mol (B) 0.0050 mol (C) 0.0090 mol (D) 0.010 mol (E) 0.020 mol Question #64 did not align with the new course and has been removed.
Unauthorized copying or reuse of any part of this page is illegal. GO ON s O THE NEXT PAGE. -19- NaOH(aq) + HCl( aq) → H 2O(l) + NaCl( aq) 65. A student is trying to determine the heat of reaction for the acid-base neutralization reaction represented above . The student uses 0.50 M NaOH and 0.50 M HCl solutions. Which of the following situations, by itself, would most likely result in the LEAST error in the calculated value of the heat of reaction? (A) The thermometer was incorrectly calibrated and read 0.5 Celsius degree too high during the procedure. (B) The volume of the acid solution added to the calorimeter was actually 1.0 mL less than what was recorded. (C) The calorimeter was poorly insulated, and some heat escaped to the atmosphere during the procedure. (D) The actual molarity of the base solution was 0.53 M but was recorded as 0.50 M. (E) The final temperature of the mixture was taken before the contents of the calorimeter had reached thermal equilibrium. 66. A molecular solid coexists with its liquid phase at its melting point. The solid-liquid mixture is heated, but the temperature does not change while the solid is melting. The best explanation for this phenomenon is that the heat absorbed by the mixture (A) is lost to the surroundings very quickly (B) is used in overcoming the intermolecular attractions in the solid (C) is used in breaking the bonds within the molecules of the solid (D) causes the nonbonding electrons in the molecules to move to lower energy levels (E) causes evaporation of the liquid, which has a cooling effect 67. The role of a catalyst in a chemical reaction is to (A) decrease the amount of reactants that must be used (B) lower the activation energy for the reaction (C) supply the activation energy required for the reaction to proceed (D) increase the amounts of products formed at equilibrium (E) increase the entropy change for the reaction 68. If 50. mL of 1.0 M NaOH is diluted with distilled water to a volume of 2.0 L, the concentration of the resulting solution is (A) 0.025 M (B) 0.050 M (C) 0.10 M (D) 0.50 M (E) 1.0 M 69. Which of the following is NOT an accepted name for the formula given? (A) CH 3OH . . methanol (B) CuO . . copper(I) oxide (C) FeCl 3 . . iron(III) chloride (D) H 2SO 4 . . sulfuric acid (E) SrCO 3 . . strontium carbonate Question #70 did not align with the new course and has been removed.
Unauthorized copying or reuse of any part of this page is illegal. GO ON s O THE NEXT PAGE. -20- 71. Which of the following molecules contains exactly three sigma ( σ) bonds and two pi ( π) bonds? (A) C 2H2 (B) CO 2 (C) HCN (D) SO 3 (E) N 2 73. Resonance is most commonly used to describe the bonding in molecules of which of the following? (A) CO 2 (B) O 3 (C) H 2O (D) CH 4 (E) SF 6 74. A student prepares a solution b y dissolving 60.00 g of glucose (molar mass 180.2 g mol − 1) in enough distilled water to make 250.0 mL of solution. The molarity of the solution should be reported as (A) 12.01 M (B) 12.0 M (C) 1.332 M (D) 1.33 M (E) 1.3 M 75. Which of the following substances is a strong electrolyte when dissolved in water? (A) Sucrose (B) Ethanol (C) Sodium nitrate (D) Acetic acid (E) Ammonia Question #72 did not align with the new course and has been removed.
-21- END OF SECTION I IF YOU FINISH BEFORE TIME IS CALLED, YOU MAY CHECK YOUR WORK ON THIS SECTION. DO NOT GO ON TO SECTION II UNTIL YOU ARE TOLD TO DO SO. MAKE SURE YOU HAVE DONE THE FOLLOWING. • PLACED YOUR AP NUMBER LABEL ON YOUR ANSWER SHE ET • WRITTEN AND GRIDDED YOUR AP NUMBER CORRECTLY ON YOU R ANSWE R SH EET • TAKEN THE AP EXAM LABEL FROM THE FRONT OF THIS BOOKLET AND PL ACED IT ON YOUR ANSWER SH EET
-22- NO TE ST MATERIAL ON THIS PAGE
-23- NO TE ST MATERIAL ON THIS PAGE
At a Glance Total Time1 hour, 30 minutes Number of Questions75 Percent of Total Score50% Writing InstrumentPencil required Electronic DeviceNone allowed Instructions Section I of this exam contains 75 multiple-choice questions.Fill in only the circles for numbers 1 through 75 of the answer sheet. Indicate all of your answers to the multiple- choice questions on the answer sheet.No credit will be given for anything written in this exam booklet, but you may use the booklet for notes or scratch work. After you have decided which of the suggested answers is best, completely fill in the corresponding circle on the answer sheet. Give only one answer to each question. If you change an answer, be sure that the previous mark is erased completely. Here is a sample question and answer. Use your time effectively, working as quickly as you can without losing accuracy. Do not spend too much time on any one question. Go on to other questions and come back to the ones you have not answered if you have time. It is not expected that everyone will know the answers to all of the multiple- choice questions. Your total score on the multiple- choice section is based only on the number of questions answered correctly. Points are not deducted for incorrect answers or unanswered questions. DO NOT OPEN THIS BOOKLET UNTIL YOU ARE TOLD TO DO SO. AP ® Chemistry Exam SECTION I: Multiple Choice 2013 Form I Form Code 4JBP4-S 25
769273 AP ® Chemistry Exam Monday morning, May 6, 2013 SECTION II: Free Response 2013 I affirm that: This exam is being administered on Monday morning ,May 6 ,2013 . I did not have advance knowledge of the free -response questions ,nor did I open the Section II booklet before being instructed to do so by the proctor . I will not take this exam booklet from the room ,and will only discuss the free -response questions if the specific questions in the exam are released on the College Board website two days after the exam administration .If the questions in this exam are not released ,I will not discuss them with anyone . I understand that if I do not place my AP number label below ,it may be impossible to identify this booklet as my own ,which could delay or jeopardize my AP score . Furthermore ,I understand and accept that my exam score may be canceled if I do not meet these conditions and initial here . ©2010 The College Board. College Board, Advanced Placement Program, AP, and the acorn logo are registered trademarks of the College Board.Unauthorized reproduction or use of any part of this test is prohibited and may result in cancellation of scores and possible prosecution to the fullest extentof the law. TEST BOOK SERIAL NUMBER *T25I* T25I Form I Form Code 4GBP2-S2 25
-2- GO ON TO THE NEXT PAGE. INFORMATION IN THE TABLE BELOW AND IN THE TABL ES ON PAGES 3-5 MAY BE USEFUL IN ANSWERING THE QUESTIONS IN THIS SECTION OF THE EXAMINATION.
-3- GO ON TO THE NEXT PAGE. STANDARD REDUCTION POTENTIALS IN AQUEOUS SOLUTION AT 25 C∞ Half-reaction (V) E∞ 2F( ) 2 ge - + Æ 2F - 2.8 7 3+ Co e- + Æ 2 Co + 1.8 2 3+ Au 3 e - + Æ Au( )s 1.5 0 2Cl ( ) 2 ge - + Æ 2Cl - 1.36 + 2 O() 4H 4 ge - ++ Æ 2 2H O( ) l 1.23 2Br ( ) 2le - + Æ 2Br - 1.07 2+ 2Hg 2e - + Æ 2+ 2 Hg 0.9 2 2+ Hg 2 e - + Æ H g()l 0.85 + Ag e - + Æ A g()s 0.8 0 2+ 2 Hg 2 e - + Æ 2H g()l 0.79 3+ Fe e - + Æ 2+ Fe 0.77 2I() 2 se - + Æ 2I - 0.53 + Cue - + Æ Cu( )s 0.5 2 2+ Cu 2 e - + Æ Cu( )s 0.3 4 2+ Cu e - + Æ + Cu 0.15 4+ Sn 2 e - + Æ 2+ Sn 0.15 + S( ) 2 H 2 se - ++ Æ 2HS( ) g 0.1 4 + 2H 2e - + Æ 2H() g 0.0 0 2+ Pb 2 e - + Æ Pb( )s –0 .13 2+ Sn 2e - + Æ Sn( )s –0 .1 4 2+ Ni 2e - + Æ Ni( )s –0 .25 2+ Co 2e - + Æ Co( )s –0 .28 2+ Cd 2e - + Æ Cd( )s –0 .4 0 3+ Cre - + Æ 2+ Cr –0 .41 2+ Fe 2e - + Æ Fe( )s –0 .4 4 3+ Cr 3e - + Æ Cr( )s –0 .7 4 2+ Zn 2e - + Æ Zn( )s –0 .7 6 2 2H O( ) 2le - + Æ 2H() + 2OH g - –0.83 2+ Mn 2 e - + Æ Mn( )s –1 .1 8 3+ Al 3e - + Æ Al( )s –1 .6 6 2+ Be 2e - + Æ Be( )s –1 .7 0 2+ Mg 2e - + Æ M g()s –2 .3 7 + Nae - + Æ Na( )s –2 .71 2+ Ca 2e - + Æ Ca( )s –2 .8 7 2+Sr 2e - + Æ Sr( )s –2 .8 9 2+ Ba 2e - + Æ Ba( ) s –2.9 0 + Rbe - + Æ Rb( ) s –2 .9 2 +Ke - + Æ K( ) s –2.9 2 + Cse - + Æ Cs( ) s –2.9 2 +Lie - + Æ Li( ) s –3.05
GO ON TO THE NEXT PAGE. -4- ADVANCED PLACEMENT CHEMISTRY EQUATIONS AND CONSTANTS energy velocity frequenc y principal quantum number wavelength mass momentum E vn m p u l == == == = 81 34 23 1 23 1 19 Speed of light, 3.0 10 m s Planck’s constant, 6.63 10 J s Boltzmann’s constant, 1.38 10 J K Avogadro’s number 6.022 10 molElectron char ge, 1.602 10 coulomb 1 electron volt per a c h k e - - -- - - =¥ =¥ =¥ =¥ =- ¥ 1l tom 96.5 kJ mo - = Equilibrium Constants (weak acid) (weak base) (water) (gas pressure) (molar concentrations) a b w p cK K K K K standard entropy standard enthalpy standard free energy standard reduction potential temperature moles mass heat specific heat capacity molar heat capacit y at constant pressure activ p a S H G E Tn m q c C E = = = = = = = = = = =D D D D ation energy rate constant frequency factor k A = = 11 11 11 11 Faraday’s constant , 96, 500 coulombs per mole of electrons Gas constant, 8.31 J mol K 0.0821 L atm mol K 62.4 L torr mol K 8.31 volt coulomb mol K R -- -- -- -- = = = = = ATOMIC STRUCTURE 18 2 2.178 10 joule n Ehv c v h =pm m E n u l l u - == = -¥ = EQU ILIBRIUM 14 [H ] [A ] [HA] [OH ] [HB ] [B] [OH ] [H ] 1.0 10 @ 25 C pH log [H ], pOH log[OH ] 14 pH pOH [A ] pH p log [HA] [HB ] pOH p log [B] p log , p log (), where moles product gas mol a b w ab a b a abb pc n K K K KK K K KKKK KKRT n +- -+ -+ - +- -+ = = = =¥ =¥ =- =- =+ =+ =+ =- =- = =- D D D es reactant gas THERMOCHEMISTRY/KINETICS products reactants products reactants products reactants ln 2.303 log ln 2.303 lo g p f f f f SS S HH H GG G GHTS RT K RT K nE G G RT Q G RT Q qmcT H C T = = =- - =- - =- =- =- =+ =+ = =ÂÂ ÂÂ ÂÂ D DD D D DD D DD DD D DD D DD D DD D DD D DD D D D D [ ] [ ] [] [] 0 0 ln A ln A 11 AA t t kt kt -=- -= ( )1 ln ln aE kA RT - =+
GO ON TO THE NEXT PAGE. -5- GASES, LIQUIDS, AND SOLUTIONS 11 2 2 12 12 21 22 , 2 () moles A where total moles ... KC273 33 1 per molecule 2 3 per mole 2 molarity, moles solu Atotal A A total A B C rmsPP PV nRT na PVnbnRT V XX PPPP m n PV P V TT m D V kT RT u m KE m KE RT r r M ʈ Á˜ ˯ =¥ = = = +-= = =+++ = =+ = == = = = D u M M M M te per liter solution molalit y moles solute per kilo gram solvent molality molality ff bbTiK TiK iMRT Aabc = =¥ =¥ = = D D p OXIDATION-REDUCTION; ELECTROCHEMISTRY cell cell cell , [C] [D] where A B C D [A] [B] 0.0592 ln lo g @25 C log 0.0592 cd ab Qa bcd q I t RT EE QE Q nn nE K =+ Æ+ = =- =- = DD D D pressure volume temperature number of moles density mass velocity P V T n D m = = = = = = = u root -mean-square speed kinetic energy rate of effusion molar mass osmotic pressure van’t Hoff factor molal freezin g-point depression constant molal boilin g-point elevation constant abs rms f buKE r i K K Ap = = = = = = = = = M orbance molar absorptivity path length concentration reaction quotient current (amperes) charge (coulombs) time (seconds) standard reduction potential equilibrium constant a b c Q I q t E K = = = = = = = = = D 11 11 11 11 23 1 1 2 1 2 1atm 7 Gas constant, 8.31 J mol K 0.0821 L atm mol K 62.4 L torr mol K 8.31 volt coulomb mol K Boltzmann’s constant, 1.38 10 J K for H O 1.86 K kg mol for H O 0.512 K kg mol f b R k K K -- -- -- -- -- - - = = = = = =¥ = = 60 mm Hg 760 torr STP 0.00 C and 1.0 atm Faraday’s constant, 96, 500 coulombs per mole of electrons = = = D
Unauthorized copying or reuse of any part of this page is illegal. GO= ON TO THE NEXT PAGE.= -6- CHEMISTRY Section II (Total time—95 minutes) Part A Time — 55 minutes YOU MAY USE YOUR CALCULATOR FOR PART A. CLEARLY SHOW THE METHOD USED AND THE STEPS INVOLVED IN ARRIVING AT YOUR ANSWERS. It is to your advantage to do this, sinc e you may obtain partial credit if you do an d you will receive little or no credit if you do not. Attention should be paid to significant figures. Be sure to write all your answers to the questions on the lined pages following each question in this booklet. Answer Questions 1, 2, and 3. The Section II score weighting for each question is 20 percent. NH 4Cl(s) Æ ¨ NH 3( g ) + HCl( g ) 1. When solid ammonium chloride is heated, it decomposes as represented above. The value of Kp for the reaction is 0.0792 at 575 K . A 10.0 g sample of solid ammonium chloride is placed in a rigid, evacuated 3.0 L container that is sealed and heated to 575 K . The sy stem comes to equilibrium with some solid NH 4Cl remaining in the container. (a) Write the expression for the equilibrium constant for the reaction in terms of partial pressures (i.e., Kp). (b) Calculate the partial pressure of NH 3( g ), in atm, at equilibrium at 575 K. (c) A small amount of NH 3( g ) is injected into the equilibrium mixt ure in the 3.0 L container at 575 K. (i) As the new equilibrium is being established at 575 K, does the amount of NH 4Cl(s) in the container increase, decrease, or remain the same? Justify your answer. (ii) After the new equilibrium is established at 575 K, is the value of Kp greater than, less than, or equal to the value before the NH 3( g ) was injected into the cont ainer? Justify your answer. (d) When the temperature of the container is lowered to 500 K, the number of moles of NH 3( g ) in the container decreases. On the basis of this observation, is the decomposition of NH 4Cl(s) endothermic or exothermic? Justify your answer. In another experiment, 20.00 mL of 0.800 M NH 4Cl( aq) is prepared. The ammonium ion reacts with water according to the equation NH 4 +( aq) + H 2O(l ) Æ ¨ NH 3( aq) + H 3O+( aq). (e) Calculate the value of the equilibrium constant fo r the reaction of the ammonium ion with water. (At 25 °C the value of Kb for NH 3 is 1.8 × 10 − 5.)
Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -7- (f) A solution is prepared by mixing 20.0 mL of 0.800 M NH 3(aq) with 20.0 mL of 0.800 M NH 4Cl(aq). Assume that volumes are additive. (i) Is the solution acidic, basic, or neutral? Justify your answer. Question #1-fii did not align with the new course and has been removed.
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Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -10- XClO 3( s) → XCl ( s) + 3 2O2( g) 2. The equation above represents the decomposition of a compound contai ning an unknown element, X . A 1.39 g sample of XClO 3(s) was completely decomposed by heating. Th e gas produced by the react ion was captured over water in a gas-collection tu be at 24.0°C. The total volume of gas in the tube was 506 mL, and the total pressure inside the tube was determined to be 739.5 torr. The vapor pressure of water is 22.4 torr at 24.0° C. (a) Calculate the partial pressure, in torr, of the O2( g ) that was collected at 24.0 ° C. (b) Calculate the number of moles of O2( g ) collected at 24.0 ° C. (c) Determine the number of moles of XClO 3( s) that de composed. (d) Determine the molar mass of the compo und. (e) Determine the identity of element X . In a different experiment, 0.470 mol of XClO 3( s) decomposed at 1.0 atm in the presence of a catalyst as a total of 21.1 kJ of heat was released. The value of 298G D D for the reaction is −121.5 kJ/mol rxn . (f) Calculate the value of 298HD D for the decomposition reaction. (g) Which is larger: the sum of the bond energies of the products or the sum of the bond energies of the reactants? Justify your answer. (h) How does the presence of a catalyst affect the value of 298G D D for the reaction? Justify your answer.
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Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -14- 2 NO ( g) + Br 2(g ) → 2 NOBr ( g ) 3. NO(g ) reacts with Br 2(g ) , as represented by the equation above. An experiment was performed to study the rate of the reaction at 546 K . Data from three trials are shown in the table below. Trial Initial [NO] (M ) Initial [Br 2] ( M ) Initial Rate of Consumption of Br 2 ( M s -1) 1 0.10 0.20 12.0 2 0.40 0.20 192. 0 3 0.10 0.60 36.0 (a) Using the data in the table, determine the order of the reaction with respect to each of the following reactants. In each case, justify your answer. (i) Br 2 (ii) NO (b) Write the rate law for the reaction. (c) Determine the value of the rate constant, k , for the reaction. Include units with your answer. Question #3-d did not align with the new course and has been removed. (e) At a later time during trial 2, the concentration of Br 2(g ) is determined to be 0.16 M. (i) Determine the concentration of NO(g ) at that time. (ii) Calculate the rate of consumption of Br 2( g ) at that time. A proposed two-step mechanism for the reaction is represented below. Step 1: NO + Br 2 → NOBr 2 slow ( rate-determining step ) Step 2: NO + NOBr 2 → 2 NOBr fast (f) Is the proposed mechanism consistent with the rate law determined in part (b) ? Justify your answer.
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-19- ADDITIONAL PAGE FOR ANSWERING QUESTION 3 STOP If you finish before time is called, you may check your work on this part only. Do not turn to the other part of the test until you are told to do so.
B B B B B B B B B B B B B B Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -20- CHEMISTRY Part B Time — 40 minutes NO CALCULATORS MAY BE USED FOR PART B. Answer Question 4 below. The Section II score weighting for this question is 10 percent. 4. For each of the following three reactions, write a bala nced equation in part (i) and answer the question in part (ii). In pa rt (i), coefficients should be in terms of lowest whole numbers. Assume that solutions are aqueous unless otherwise indicated. Represent su bstances in solutions as ions if the substances are extensively ionize d. Omit formula s for any ions or molecules that are uncha nged by the reaction. You may use the empty space at the bottom of the next page for scratch work, but only equa tions that are written in the answer boxes provided will be scored. (a) Magnesium metal is strongly heated in a sm all porcelain container in the presence of oxygen. (i) Balanced equation: (ii) Does the mass of the material in the container increase, decrease, or remain the same as the reaction proceeds? Explain. ______________________________________________________________________________________ ______________________________________________________________________________________ ______________________________________________________________________________________
B B B B B B B B B B B B B B Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -21- (c) A solution of silver(I) nitrate is mixed with a solution of potassium sulfide. (ii) Identify the spectator ions in the reaction that occurs. ______________________________________________________________________________________ ______________________________________________________________________________________ ______________________________________________________________________________________ YOU MAY USE THE SPACE BELOW FOR SCRATCH WORK, BUT ONLY EQUATIONS THAT ARE WRITTEN IN THE ANSWER BOXES PROVIDED WILL BE SCORED. Question #4-b did not align with the new course and has been removed. Question #4-ci did not align with the new course and has been removed.
B B B B B B B B B B B B B B Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -22- Answer Question 5 and Question 6. The Section II scor e weighting for these questions is 15 percent each. Your responses to these questions will be scored on the basis of the accuracy and relevance of the information cited. Explanations should be clear and well organized. Examples and equations may be included in your responses where appropriate. Specific answers are preferab le to broad, diffuse responses. 5. A student is asked to prepare 100.0 mL of 1.000 × 10 −2 M Na 2SO 4( aq) to use in a precipitation experiment. The student first weighs out 0. 1420 g of solid Na 2SO 4. (a) The balance used to measure the mass of the Na 2SO 4( s) must have a certain minimum level of precision to ensure that the concentration of the Na 2SO 4 solution can be known to four significant figures. If this minimum level of precision of the balance is expressed as ± x mg , what is the value of x ? (b) Describe how the student can best prepare 100.0 mL of 1.000 × 10 − 2 M Na 2SO 4( aq) after the appropriate mass of solid Na 2SO 4 has been measured. Circle each item used from the list below and describe the essential steps in the procedure for preparing the solution. 50 mL buret 100 mL Erlenmeyer flask Distilled water 50 mL volumetric flask 100 mL volumetric flask Dropper 100 mL beaker 100 mL graduated cylinder Squeeze bottle 10 mL volumetric pipet The student is given 250 mL of a solution containing the following cations: Ba 2+, Ca 2+, Pb 2+, and Sr2+. The concentration of each of these cations in the solution is 1.0 M. (c) In the first experiment, the student puts 10 mL of the Ba 2+/Ca 2+/Pb 2+/Sr 2+ solution in a test tube and then adds 1.000 × 10 −2 M Na 2SO 4( aq) one drop at a time, swirling the contents of the test tube afte r each drop is added. Based on the inf ormation in the table below, which salt will be the first to precipitate in the test tube? Justify your answer. Salt BaSO 4 CaSO 4 PbSO 4 SrSO 4 Ksp at 25° C 1.5 × 10 −9 6.1 × 10 −5 1.3 × 10 −8 3.2 × 10 −7 (d) In a second experiment, the student electrolyzes the Ba 2+/Ca 2+/Pb 2+/Sr 2+ solution by putting 100 mL of the solution in a beaker and immersing two platinum electr odes in the solution. The electrodes are connected to a source of DC voltage, as shown in the following diag ram. The voltage source has a dial that allows the student to increase the voltage slowly. In doing so, the student observes that one of the metals is deposited (plates out) on one of the electrodes.
B B B B B B B B B B B B B B Unauthorized copying or reuse of any part of this page is illegal. GO ON s O THE NEXT PAGE. -23- (i) On the diagram, circle the electrode on which the metal plates out. Justify your answer. (ii) Identify the metal that plates out. Justify your answer. Question #5-e did not align with the new course and has been removed.
B B B B B B B B B B B B B B GO ON TO THE NEXT PAGE. -24- ADDITIONAL PAGE FOR ANSWERING QUESTION 5
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