Related Files | 12
Short Page Link
https://www.edufilestorage.com/6la
Full Page Link
https://www.edufilestorage.com/6la/PDF_2013_AP_Chemistry_Practice_Exam_MCQ_Multiple_Choice_Questions_with_Answers_Advanced_Placement.pdf
HTML Code
<a href="https://www.edufilestorage.com/6la/PDF_2013_AP_Chemistry_Practice_Exam_MCQ_Multiple_Choice_Questions_with_Answers_Advanced_Placement.pdf" target="_blank" title="Download from eduFileStorage.com"><img src="https://www.edufilestorage.com/cache/plugins/filepreviewer/4376/pdf/150x190_middle_46f4e7862b1eb5bd4935adbbba5d79e8.jpg"/></a>
Forum Code
[url=https://www.edufilestorage.com/6la/PDF_2013_AP_Chemistry_Practice_Exam_MCQ_Multiple_Choice_Questions_with_Answers_Advanced_Placement.pdf][img]https://www.edufilestorage.com/cache/plugins/filepreviewer/4376/pdf/150x190_middle_46f4e7862b1eb5bd4935adbbba5d79e8.jpg[/img][/url]
| Filename: | [PDF] 2013 AP Chemistry Practice Exam MCQ Multiple Choice Questions with Answers Advanced Placement.pdf |
| Filesize: | 3.44 MB |
| Keywords: | |
| Description: | Download file or read online AP past exam paper 2013 AP Chemistry Practice Exam MCQ Multiple Choice Questions with Answers and FRQ Free Response Questions with Scoring Guidelines - Collegeboard Advanced Placement. |
[PDF] 2013 AP Chemistry Practice Exam MCQ Multiple Choice Questions with Answers Advanced Placement.pdf | Plain Text
Chemistry Practice Exam and \FNotes Effective Fall 201\b
Chemistry Practice\5 Exam 2 About the College \qBoard ® The College Board is a mission-driven not-for-profit organization that \bonne\bts students to \bollege su\b\bess and opportunity. Founded in 1900, the College Board was \breated to expand a\b\bess to higher edu\bation. Today, the membership asso\biation is made up of over 6,000 of the world’s leading edu\bational institutions and is dedi\bated to promoting ex\bellen\be and equity in edu\bation. Ea\bh year, the College Board helps more than seven million students prepare for a su\b\bessful transition to \bollege through programs and servi\bes in \bollege readiness and \bollege su\b\bess — in\bluding the SAT® and the Advan\bed Pla\bement Program®. The organization also serves the edu\bation \bommunity through resear\bh and advo\ba\by on behalf of students, edu\bators, and s\bhools. For further information visit www.collegeboard.org. AP Equity and Acce\b\b P\qolicy The College Board strongly en\bourages edu\bators to make equitable a\b\bess a guiding prin\biple for their AP programs by giving all willing and a\bademi\bally prepared students the opportunity to parti\bipate in AP. We en\bourage the elimination of barriers that restri\bt a\b\bess to AP for students from ethni\b, ra\bial and so\bioe\bonomi\b groups that have been traditionally underserved. S\bhools should make every effort to ensure their AP \blasses refle\bt the diversity of their student population. The College Board also believes that all students should have a\b\bess to a\bademi\bally \bhallenging \bourse work before they enroll in AP \blasses, whi\bh \ban prepare them for AP su\b\bess. It is only through a \bommitment to equitable preparation and a\b\bess that true equity and ex\bellen\be \ban be a\bhieved. Important Note This Pra\bti\be Exam is provided by the College Board for AP Exam preparation. Tea\bhers are permitted to download the materials and make \bopies to use with their students in a \blassroom setting only. To maintain the se\burity of this exam, tea\bhers should \bolle\bt all materials after their administration and keep them in a se\bure lo\bation. Exams may not be posted on s\bhool or personal websites, nor ele\btroni\bally redistributed for any reason. Further distribution of these materials outside of the se\bure College Board site disadvantages tea\bhers who rely on un\bir\bulated questions for \blassroom testing. Any additional distribution is in violation of the College Board’s \bopyright poli\bies and may result in the termination of Pra\bti\be Exam a\b\bess for your s\bhool as well as the removal of a\b\bess to other online servi\bes su\bh as the AP Tea\bher Community and Online S\bore Reports. © 2013 The College Board. College Board, Advan\bed Pla\bement Program, AP, and the a\born logo are registered trademarks of the College Board. All other produ\bts and servi\bes may be trademarks of their respe\btive owners.
3 Chemistry Practice\5 Exam Contents INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 I. PR\bCTICE EX\bM Exam Content and Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Administering the Pra\bti\be Exam . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Student Answer Sheet for Multiple-Choi\be Se\btion . . . . . . . . . . . . . . . 9 AP® Chemistry Pra\bti\be Exam . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Periodi\b Table of the Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Chemistry Equations and Constants . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 II. NOTES ON THE PR\bCTICE EX\bM Introdu\btion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 Multiple-Choi\be Se\btion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 Free-Response Se\btion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Chemistry Practice\5 Exam 4 Introduction Beginning in May 2014, the AP Chemistry Exam will assess understanding of \bhemistry prin\biples, \bontent, and \bon\bepts in \bombination with s\bien\be pra\bti\bes. The revised exam will \bontinue to feature multiple-\bhoi\be and free-response questions. Se\btion I will have 60 multiple-\bhoi\be questions, with up to 50 per\bent of the questions falling within sets of multiple-\bhoi\be questions. Question sets provide a single stimulus or set of data and 2 to 6 related questions. Se\btion II will \bonsist of 7 free-response questions, with 3 long questions and 4 short questions. Part I of this publi\bation is the Pra\bti\be Exam. This will mirror the look and feel of an a\btual AP Exam, in\bluding instru\btions and sample questions. However, these exam items have never been administered in an operational exam, and, therefore, statisti\bal analysis is not available. The purpose of this se\btion is to provide edu\bators with sample exam questions that a\b\burately refle\bt the \bomposition/ design of the revised exam and to offer these questions in a way that gives tea\bhers the opportunity to test their students in an exam situation that \blosely resembles the a\btual exam administration. Part II is the Notes on the Pra\bti\be Exam. This se\btion offers detailed explanations of how ea\bh question in the pra\bti\be exam links ba\bk to the AP Chemistry Curriculum Framework (Notes) in order to provide a \blear link between \burri\bulum and assessment. It also explains why the \borre\bt answer is the \borre\bt \bhoi\be and why the other answers are in\borre\bt (Rationales). How AP Courses and Exams Are Deve\boped AP \bourses and exams are designed by \bommittees of \bollege fa\bulty and AP tea\bhers who ensure that ea\bh AP \bourse and exam refle\bts and assesses \bollege- level expe\btations. These \bommittees define the s\bope and expe\btations of the \bourse, arti\bulating through a \burri\bulum framework what students should know and be able to do upon \bompletion of the AP \bourse. Their work is informed by data \bolle\bted from a range of \bolleges and universities to ensure that AP \bourse work refle\bts \burrent s\bholarship and advan\bes in the dis\bipline. These same \bommittees are also responsible for designing and approving exam spe\bifi\bations and exam questions that \blearly \bonne\bt to the \burri\bulum framework. The AP Exam development pro\bess is a multi-year endeavor; all AP Exams undergo extensive review, revision, piloting, and analysis to ensure that questions are high quality and fair and that the questions \bomprise an appropriate range of diffi\bulty. Throughout AP \bourse and exam development, the College Board gathers feedba\bk from se\bondary and post-se\bondary edu\bators. This feedba\bk is \barefully \bonsidered to ensure that AP \bourses and exams provide students with a \bollege- level learning experien\be and the opportunity to demonstrate their qualifi\bations for advan\bed pla\bement and \bollege \bredit upon \bollege entran\be.
5 Chemistry Practice\5 Exam Cour\be Development Ea\bh \bommittee first arti\bulates its dis\bipline’s high-level goals and then identifies the \bourse’s spe\bifi\b learning obje\btives. This approa\bh is \bonsistent with “ba\bkward design,” the pra\bti\be of developing \burri\bula, instru\btion, and assessments with the end goal in mind. The learning obje\btives des\bribe what students should know and be able to do, thereby providing \blear instru\btional goals as well as targets of measurement for the exam. Exam Development Exam development begins with the \bommittee making de\bisions about the overall nature of the exam. How long will it be? How many multiple-\bhoi\be questions? How many free-response questions? How mu\bh time will be devoted to ea\bh se\btion? How will the \bourse \bontent and skills be distributed a\bross ea\bh se\btion of the exam? Answers to these questions be\bome part of the exam spe\bifi\bations. With the exam spe\bifi\bations set, test developers design questions that \bonform to these spe\bifi\bations. The \bommittee reviews every exam question for alignment with the \burri\bulum framework, \bontent a\b\bura\by, and a number of other \briteria that ensure the integrity of the exam. Exam questions are then piloted in AP \blassrooms to determine their statisti\bal properties. Questions that have been approved by the \bommittee and piloted su\b\bessfully are in\bluded in an exam. When an exam is assembled, the \bommittee \bondu\bts a final review of the exam to ensure overall \bonformity with the spe\bifi\bations. How AP Exams Are Scored The exam s\boring pro\bess, like the \bourse and exam development pro\bess, relies on the expertise of both AP tea\bhers and \bollege fa\bulty. While multiple-\bhoi\be questions are s\bored by ma\bhine, the free-response questions are s\bored by thousands of \bollege fa\bulty and expert AP tea\bhers at the annual AP Reading. AP Exam Readers are thoroughly trained, and their work is monitored throughout the Reading for fairness and \bonsisten\by. In ea\bh subje\bt, a highly respe\bted \bollege fa\bulty member fills the role of Chief Reader, who, with the help of AP Readers in leadership positions, maintains the a\b\bura\by of the s\boring standards. S\bores on the free-response questions are weighted and \bombined with the results of the \bomputer-s\bored multiple-\bhoi\be questions, and this raw s\bore is summed to give a \bomposite AP s\bore of 5, 4, 3, 2, or 1. The s\bore-setting pro\bess is both pre\bise and labor intensive, involving numerous psy\bhometri\b analyses of the results of a spe\bifi\b AP Exam in a spe\bifi\b year and of the parti\bular group of students who took that exam. Additionally, to ensure alignment with \bollege-level standards, part of the s\bore-setting pro\bess involves \bomparing the performan\be of AP students with the performan\be of students enrolled in \bomparable \bourses in \bolleges throughout the United States. In general, the AP \bomposite s\bore points are set so that the lowest raw s\bore needed to earn an AP s\bore of 5 is equivalent to the average s\bore among \bollege students earning grades of A in the \bollege \bourse. Similarly, AP Exam s\bores of 4 are equivalent to \bollege grades of A–, B+, and B. AP Exam s\bores of 3 are equivalent to \bollege grades of B–, C+, and C.
Chemistry Practice\5 Exam 6 Using and Interpreting AP Scores The extensive work done by \bollege fa\bulty and AP tea\bhers in the development of the \bourse and the exam and throughout the s\boring pro\bess ensures that AP Exam s\bores a\b\burately represent students’ a\bhievement in the equivalent \bollege \bourse. While \bolleges and universities are responsible for setting their own \bredit and pla\bement poli\bies, AP s\bores signify how qualified students are to re\beive \bollege \bredit and pla\bement:\bP Score Qualification5 Extremely well qualified 4 Well qualified 3 Qualified 2 Possibly qualified 1 No re\bommendation Additiona\b Resources Visit ap\bentral.\bollegeboard.org for more information about the AP Program.
7 Chemistry Practice\5 Exam Practice Exam Exam Content and For\qmat The AP Chemistry Exam is approximately 3 hours in length. There are two se\btions:• Se\btion I is 90 minutes in length and \bonsists of 60 multiple-\bhoi\be questions a\b\bounting for 50 per\bent of the final s\bore. • Se\btion II is 90 minutes in length and \bonsists of 3 long free-response questions and 4 short free-response questions a\b\bounting for 50 per\bent of the final s\bore. Students \ban budget the full 90 minutes however they wish, but the 3 long questions should take about 15–20 minutes ea\bh to answer, and the 4 short questions should take about 7–10 minutes ea\bh to answer. Admini\btering the Pra\qctice Exam This se\btion \bontains instru\btions for administering the AP Chemistry Pra\bti\be Exam. You may wish to use these instru\btions to \breate an exam situation that resembles an a\btual administration. If so, read the indented, boldfa\be dire\btions to the students; all other instru\btions are for administering the exam and need not be read aloud. Before beginning testing, have all exam materials ready for distribution. These in\blude test booklets, answer sheets, the AP Chemistry Periodi\b Table, the AP Chemistry Equations and Constants list, and \bal\bulators. SECTION I: Multiple-Choice Questions When you are ready to begin Se\btion I, say: Section I is the multiple-choice portion of the exam. Mark all of your responses on your answer sheet, one response per question. If you need to erase, do so carefully and completely. Your score on the multiple- choice section will be based solely on the number of questions answered correctly. You may NOT use a calculator. However, you may use the Periodic Table and the Equations and Constants list. \bre there any questions? You have 1 hour and 30 minutes for this section. Open your Section I booklet and begin. Note Start Time here______. Note Stop Time here______. Che\bk that students are marking their answers in pen\bil on their answer sheets, and that they are not looking at their Se\btion II booklets. After 1 hour and 30 minutes, say: Stop working. I will now collect your Section I booklet. There is a 10-minute break between Se\btions I and II. When all Se\btion I materials have been \bolle\bted and a\b\bounted for and you are ready for the break, say: Please listen carefully to these instructions before we take a 10-minute break. Everything you placed under your chair at the beginning of the exam must stay there. Leave your Section II packet on your desk during the break. \bre there any questions? You may begin your break. Testing will resume at _______.
Chemistry Practice\5 Exam 8 SECTION II: Free-Response Questions After the break, say:You have 90 minutes to answer the questions in this section. You are responsible for pacing yourself, and may proceed freely from one question to the next. Write your answers on the lined pages provided for each question. If you need more paper during the exam, raise your hand. \bt the top of each extra piece of paper you use, be sure to write your name and the number of the question you are working on. You may use a scientific/graphing calculator, the Periodic Table, and the Equations and Constants list during this ENTIRE section. \bre there any questions? You have 1 hour and 30 minutes for this section. Open your Section II booklet and begin. Note Start Time here______. Note Stop Time here______. Che\bk that students are writing their answers in their exam booklets. After 1 hour and 20 minutes, say: There are 10 minutes remaining. After 10 minutes, say: Stop working and close your exam booklet. Put your exam booklet on your desk, face up. Remain in your seat, without talking, while the exam materials are collected. If any students used extra paper for the free-response se\btion, have those students staple the extra sheet/s to the first page \borresponding to that question in their exam booklets. Colle\bt a Se\btion II booklet from ea\bh student and \bhe\bk that ea\bh student wrote answers on the lined pages \borresponding to ea\bh question. Then say: You are now dismissed.
9 Chemistry Practice\5 Exam AP ® Chemistry Student Answer Shee\wt for Multiple\bChoice Section No.An\bwer No.An\bwer 1 31 2 32 3 33 4 34 5 35 6 36 7 37 8 38 9 39 10 40 11 41 12 42 13 43 14 44 15 45 16 46 17 47 18 48 19 49 20 50 21 51 22 52 23 53 24 54 25 55 26 56 27 57 28 58 29 59 30 60 Name:
Chemistry Practice\5 Exam \b0 At a Glance Total Time1 hour, 30 minutes Number of Questions60 Percent of Total Score50% Writing InstrumentPencil required Electronic \beviceNone \bllowed Instructions Section I of this exam contains 60 multiple-choice questions .Indicate all of your ans\bers to the multiple -choice questions on the ans\ber sheet .No credit \bill be given for anything \britten in this exam booklet ,but you may use the booklet for notes or scratch \bork .After you have decided \bhich of the suggested ans\bers is best ,mark your response on your ans\ber sheet .Give only one ans\ber to each question .If you change an ans\ber ,be sure that the previous mark is erased completely .Here is a sample question and ans\ber . Use your time effectively ,\borking as quickly as you can \bithout 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 ans\bered if you have time .It is not expected that everyone \bill kno\b the ans\bers to all of the multiple -choice questions . Your total score on the multiple -choice section is based only on the number of questions ans\bered correctly .Points are not deducted for incorrect ans\bers or unans\bered questions . \bO NOT OPEN THIS BOOKLET UNTIL YOU ARE TOL\b TO \bO SO. AP ® Chemistry Practice Exam SECTION I: Mu\btip\be Choice Questions -
\b\b Chemistry Practice\5 Exam INFORMATION IN THE TABLE BELOW AND ON THE FOLLOWING PAGES MAY BE USEFUL IN ANSWERING THE QUESTIONS IN THIS SECTION OF THE EXAMINATION.
Chemistry Practice\5 Exam \b2 ADVANCED PLACEMENT CHEMIST RY EQUATIONS AND CONSTANTS Throughout the test the following symbols have th e definitions specified unless otherwise noted\b L, mL = liter(s), milliliter(s) mm Hg = millimeters of mercury g = gram(s) J, kJ = joule(s), kilojoule(s) nm = nanometer(s) V = volt(s) atm = atmosphere(s) mol = mole(s) ATOMIC STRUCTURE E = h ν c = λν E = energy ν = frequency λ = wavelength Planck’s constant, h = 6\b626 × 10 −34 J s Speed of light, c = 2\b998 × 10 8 m s −1 Avogadro’s number = 6\b022 × 10 23 mol −1 Electron charge, e = − 1\b602 × 10 −19 coulomb EQUILIBRIUM K c = [C] [D] [A] [B] c d a b , where a A + b B R c C + d D K p = C A B( ) ( )( ) ( ) c d D a b P P P P K a = [H ][A ] [HA] + - K b = [OH ][HB ] [B] - + K w = [H +][OH −] = 1\b0 ×10 −14 at 25 °C = K a × K b pH = −log [H +] , pOH = −log [OH −] 14 = pH + pOH pH = p K a + log [A ] [HA] - p K a = −log K a, pK b = −log K b Equilibrium Constants K c (molar concentrations) K p (gas pressures) K a (weak acid) K b (weak base) K w (water) KINETICS ln[A] t − ln[A] 0 = −kt [ ] [ ] 0 A A 1 1 t - = kt t ½ = 0\b693 k k = rate constant t = time t ½ = half-life
\b3 Chemistry Practice\5 Exam GASES, LIQUIDS, AND SOLUTIONS PV = nRT P A = P total × X A, where X A = moles A total moles P total = P A + P B + P C + . . . n = m M K = ° C + 273 D = m V KE per mole\bule = 1 2m v 2 Molarity, M = moles of solute per liter of solution A = a b c 1 1 pressure volume temperature number of moles mass molar mass density kineti\b energy velo\bity absorban\be molar absorptivity path length \bon\bentration Gas \bonstant, 8.314 J mol K 0.08206 P V T n m D KE Aa b c R Ã - - = = = = = = = = = = = = = = = M 1 1 1 1 L atm mol K 62.36 L torr mol K 1 atm 760 mm Hg 760 torr STP 0.00 C and 1.000 atm - - - - = = = = D THERMOCHEMISTRY/ ELECTROCHEMISTRY produ\bts rea\btants produ\bts rea\btants produ\bts rea\btants ln f f f f q mc T \b \b \b H H H G G G G H T \b RT K n F E q I tD D D D D D D D D D D = = - Â Â = - Â Â = - Â Â = - = - = - D D D D D D D D D D D D D heat mass spe\bifi\b heat \bapa\bity temperature standard entropy standard enthalpy standard free energy number of moles standard redu\btion potential \burrent (amperes) \bharge (\boulombs)t q m c T \b H G n E I q t = = = = = = = = = = = = D D D D ime (se\bonds) Faraday’s \bonstant , 96, 485 \boulombs per mole of ele\btrons 1 joule 1 volt 1 \boulomb F = =
Chemistry Practice\5 Exam \b4 GO ON TO THE NEXT PAGE. CHEMISTRY Section I 60 Multiple-Choice \buestions (Time—90 minutes) YOU MAY NOT USE YOUR CAL CULATOR FOR SECTION I Note: For all questions, assume that the temperature is 298 K, the pressure is 1.\b\b atmosphere, and solutions are aqueous unless otherwise specified. Directions: Each of the questions or incomplete statements below is followed by four suggested answers or completions. Select the answer that is best in each case and then fill in the corresponding circle on the answer sheet. 1. Complete combustion of a sample of a hydrocarbon in excess oxygen produces equimolar quantities of car bon dioxide and water. Which of the following could be the molecular formula of the compound? (A) C 2H2 (B) C 2H6 (C) C 4H8 (D) C 6H6 Substance Equilibrium Vapor Pressure at 2\b °C (torr) C6H6(l) 75 C2H5OH( l) 44 CH 3OH(l) 92 C2H6O2(l) \b.\b6 2. Based on the data in the table above, which of the following liquid substances has the weakest intermolecular forces? (A) C 6H6(l) (B) C 2H5OH( l) (C) CH 3OH( l) (D) C 2H6O2( l) Ion Ionic Radius (pm) Zn 2+ 74 Ca 2+ 1\b\b Ba 2+ 135 3. Based on the data in the table above, which of the following correctly predicts the relative strength of the attraction of Zn 2+, Ca 2+, and Ba 2+ ions to water molecules in a solution, from strongest to weakest, and provides the correct reason? (A) Zn 2+ > Ca 2+ > Ba 2+ because the smaller ions have a stronger coulombic attraction to water (B) Zn 2+ > Ca 2+ > Ba 2+ because the smaller ions are more electronegative (C) Ba 2+ > Ca 2+ > Zn 2+ because the larger ions are more polarizable (D) Ba 2+ > Ca 2+ > Zn 2+ because the larger ions are less electronegative 4. Zn( s) is used to reduce other compounds in chemical reactions. If a chemist needs a substance that is more effective in its reducing ability, which of the following species would be the best choice? (A) Na (B) H + (C) K+ (D) Cl −
\b5 Chemistry Practice\5 Exam GO ON TO THE NEXT PAGE. 5. In the diagram above, which of the labeled arrows identifies h\bdrogen bonding in water? (A) A (B) B (C) C (D) D 6. A kinetics experiment is set up to collect the gas that is generated when a sample of chalk, consisting primaril\b of solid CaCO 3, is added to a solution of ethanoic acid, CH 3COOH. The rate of reaction between CaCO 3 and CH 3COOH is determined b\b measuring the volume of gas generated at 25 ∞C and 1 atm as a function of time. Which of the following experimental conditions is most likel\b to increase the rate of gas production? (A) Decreasing the volume of ethanoic acid solution used in the experiment (B) Decreasing the concentration of the ethanoic acid solution used in the experiment (C) Decreasing the temperature at which the experiment is performed (D) Decreasing the particle size of the CaCO 3 b\b grinding it into a fine powder H 2( g ) + I 2(g ) Æ ¨ 2 HI(g ) 7. At 450 ∞C, 2.0 moles each of H2(g ), I2(g ), and HI( g) are combined in a 1.0 L rigid container. The value of Kc at 450 ∞C is 50. Which of the following will occur as the s\bstem moves toward equilibrium? (A) More H2( g ) and I2(g ) will form. (B) More HI( g) will form. (C) The total pressure will decrease. (D) No net reaction will occur, because the number of molecules is the same on both sides of the equation.
Chemistry Practice\5 Exam \b6 GO ON TO THE NEXT PAGE. 8. The graph above shows the speed distribution of mole\bules in a sample of a gas at a \bertain temperature. Whi\bh of the following graphs shows the speed distribution of the same mole\bules at a lower temperature (as a dashed \burve) ? (A) (B) (C) (D) 9. A 100 g sample of a metal was heated to 100 ∞C and then qui\bkly transferred to an insulated \bontainer holding 100 g of water at 22 ∞C. The temperature of the water rose to rea\bh a final temperature of 35 ∞C. Whi\bh of the following \ban be \bon\bluded? (A) The metal temperature \bhanged more than the water temperature did; therefore the metal lost more thermal energy than the water gained. (B) The metal temperature \bhanged more than the water temperature did, but the metal lost the same amount of thermal energy as the water gained. (C) The metal temperature \bhanged more than the water temperature did; therefore the heat \bapa\bity of the metal must be greater than the heat \bapa\bity of the water. (D) The final temperature is less than the average starting temperature of the metal and the water; therefore the total energy of the metal and water de\breased.
\b7 Chemistry Practice\5 Exam GO ON TO THE NEXT PAGE. 10. The elements I and Te have similar average atomic masses. A sample th at \bas believed to be a mixture of I and Te \bas run through a mass spectrometer, resulting in the data above. All of the follo\bing statements are true. Which one \bould be the best basis for concluding that the sample \bas pure Te? (A) Te forms ions \bith a −2 charge, \bhereas I forms ions \bith a −1 charge. (B) Te is more abundant than I in the universe. (C) I consists of only one naturally occurring isotope \bith 74 neutrons, \bhereas Te has more than one isotope. (D) I has a higher first ionization energy than Te does. H 2C2O4( aq ) + H 2O( l) Æ ¨ H 3O+( aq ) + HC 2O4−( aq ) HC 2O4 −( aq ) + H 2O( l) Æ ¨ H 3O+( aq ) + C 2O42 − (aq ) H 2O( l) + H 2O( l) Æ ¨ H 3O+( aq ) + OH −(aq ) 11. All the reactions represented above occur in an aqueous solution of oxalic acid. Which of the follo\bing represent a Brønsted-Lo\bry conjugate acid-base pair? (A) H 2C2O4(aq ) and C2O42 - (aq ) (B) HC 2O4 −( aq ) and C2O42 - (aq ) (C) HC 2O4 -( aq ) and H2O( aq) (D) H 3O+( aq ) and OH −(aq )
Chemistry Practice\5 Exam \b8 GO ON TO THE NEXT PAGE. 12. Which of the following reactions is not thermodynamically favored at low tem\beratures but becomes favored as the tem\berature increases? Reaction D H ° (kJ/mol rxn ) D S° (J/(mol rxn K)) (A) 2 CO( g) + O 2(g ) Æ 2 CO 2(g ) − 566 −173 (B) 2 H 2O(g) Æ 2 H 2(g ) + O 2(g ) 484 90.0 (C) 2 N 2O(g) Æ 2 N 2(g ) + O 2(g ) − 164 149 (D) PbCl 2(s) Æ Pb 2+(aq ) + 2 Clˉ( aq) 23.4 −12.5
\b9 Chemistry Practice\5 Exam GO ON TO THE NEXT PAGE. 13. Which of the following particulate diagrams \best s hows the formation of water vapor from hydrogen gas and oxygen gas in a rigid container at 125 ∞C ? (A) (B) (C) (D)
Chemistry Practice\5 Exam 20 GO ON TO THE NEXT PAGE. Questions 14-17 refer to the following. A 50.0 mL sample of an acid, HA, of unknown mola\bity is tit\bated, and the pH of the \besulting solution is measu\bed with a pH mete\b and g\baphed as a function of the volume of 0.100 M NaOH added. 14. At point R in the tit\bation, which of the following species has the highest concent\bation? (A) HA (B) A - (C) H 3O+ (D) OH - 15. Which of the following is the best pa\bticulate \bep\besentation of the species (othe\b than H 2O) that a\be p\besent in significant concent\bations in the solution at point U in the tit\bation? (A) (B) (C) (D)
2\b Chemistry Practice\5 Exam
Chemistry Practice\5 Exam 22 GO ON TO THE NEXT PAGE. Questions 18-20 refer to three gases in identical rigid containers under the conditions given in the ta\ble \below. Container A B C Gas Methane Ethane Butane Formula CH 4 C 2H\b C4H10 Molar mass (g/mol) 1\b 30. 58 Temperature (∞C) 27 27 27 Pressure (atm) 2.0 4.0 2.0 18. The average kinetic energy of the gas molecules is (A) greatest in container A (B) greatest in container B (C) greatest in container C (D) the same in all three containers 19. The density of the gas, in g/L, is (A) greatest in container A (B) greatest in container B (C) greatest in container C (D) the same in all three containers 20. If the pressure of each gas is increased at constant temperature until condensation occurs, which gas will condense at the lowest pressure? (A) Methane (B) Ethane (C) Butane (D) All the gases will condense at the same pressure. 21. The mass percent of carbon in pure glucose, C \bH12O\b, is 40.0 percent. A chemist analyzes an impure sample of glucose and determines that the mass percent of carbon is 38.2 percent. Which of the following impurities could account for the low mass percent of carbon in the sample? (A) Water, H 2O (B) Ribose, C 5H10O5 (C) Fructose, C \bH12O\b, an isomer of glucose (D) Sucrose, C 12H22O11 22. Caffeine (C 8H10N4O2) is a weak base with a Kb value of 4 ¥ 10 - 4. The pH of a 0.01 M solution of caffeine is in the range of (A) 2–3 (B) 5–\b (C) 7–8 (D) 11–12 23. Lewis electron-dot diagrams for CO 2 and SO 2 are given above. The molecular geometry and polarity of the two substances are (A) the same because the molecular formulas are similar (B) the same because C and S have similar electronegativity values (C) different because the lone pair of electrons on the S atom make it the negative end of a dipole (D) different because S has a greater number of electron domains (regions of electron density) surrounding it than C has 2 NO(g) + O 2(g ) Æ 2 NO 2(g ) 24. Consider the following mechanism for the reaction represented above. Step 1: 2 NO Æ ¨ N 2O2 ( fast reversible ) Step 2: N 2O2 + O 2 Æ 2 NO 2 ( slow ) Which of the following statements is true? (A) Step 1 represents a unimolecular reaction. (B) Increasing the concentration of NO will decrease the overall rate of the reaction. (C) Raising the temperature will have no effect on the numerical value of the rate constant. (D) The rate law that is consistent with the mechanism is rate = k[NO] 2[O 2].
23 Chemistry Practice\5 Exam GO ON TO THE NEXT PAGE. 25. The diagram above shows molecules of Br 2 a\bd I2 draw\b to the same scale. Which of the followi\bg is the best expla\batio\b for the differe\bce i\b the boili\bg poi\bts of liquid Br 2 a\bd I2, which are 59 ∞C a\bd 184∞C , respectively? (A) Solid iodi\be is a \betwork covale\bt solid, whereas solid bromi\be is a molecular solid. (B) The covale\bt bo\bds i\b I2 molecules are weaker tha\b those i\b Br 2 molecules . (C) I 2 molecules have electro\b clouds that are more polarizable tha\b those of Br 2 molecules, thus Lo\bdo\b dispersio\b forces are stro\bger i\b liquid I2. (D) Bromi\be has a greater electro\begativity tha\b iodi\be, thus there are stro\bger dipole-dipole forces i\b liquid bromi\be tha\b i\b liquid iodi\be.
Chemistry Practice\5 Exam 24 GO ON TO THE NEXT PAGE. 26. The figure above represents three sealed 1.\b L vesse ls, each containing a different inert gas at 298 K. The pressure of Ar in the first vessel is 2.\b atm. The ratio of the numbers of Ar, Ne, and He atoms in the vessels is 2 : 1 : 6, respectively. After all the gases are combined in a prev iously evacuated 2.\b L vessel, what is the total pressure of the gases at 298 K? (A) 3.\b atm (B) 4.5 atm (C) 9.\b atm (D) 18 atm 27. The dissolution of an ionic solute in a polar solvent can be imagined as occurring in three steps, as shown in the figure above. In step 1, the separation between ions in the solute is greatly increased, just as will occur when the solute dissolves in the polar solvent. In step 2, the polar solvent is expanded to make spaces that the ions will occupy. In the last step, the ions are inserted into th e spaces in the polar solvent. Which of the following best describes the enthalpy change, Δ H , for each step? (A) All three steps are exothermic. (B) All three steps are endothermic. (C) Steps 1 and 2 are exothermic, and the final step is endothermic. (D) Steps 1 and 2 are endothermic, and the final step is exothermic.
25 Chemistry Practice\5 Exam GO ON TO THE NEXT PAGE. Ag +( aq ) + Cl −(aq ) Æ ¨ AgCl( s) 28. A student mixes dilute AgNO 3( aq ) \bith excess NaCl( aq) to form AgCl( s), as represented by the net ionic equation above. Which of the diagrams belo\b best re presents the ions that are present in significant concentrations in the solution? ( K sp for AgCl is 1.8 ¥ 10 −10 .)
Chemistry Practice\5 Exam 26 GO ON TO THE NEXT PAGE. Questions 29-33 refer to the following. PCl 5( g ) Æ ¨ PCl 3( g ) + Cl 2(g ) PCl 5(g ) decomposes into PCl 3(g ) and Cl 2(g ) according to t\be equation above. A pure sample of PCl 5(g ) is placed in a rigid, evacuated 1.00 L container. T\be initial pressure of t\be PCl 5( g ) is 1.00 atm. T\be temperature is \beld constant until t\be PCl 5( g ) reac\bes equilibrium wit\b its decomposition products. T\be figures below s\bow t\be initial and equilib rium conditions of t\be system. 29. W\bic\b of t\be following is t\be most likely cause for t\be increase in pressure observed in t\be container as t\be reaction reac\bes equilibrium? (A) A decrease in t\be strengt\b of intermolecular attractions among molecules in t\be flask (B) An increase in t\be strengt\b of intermolecular attractions among molecules in t\be flask (C) An increase in t\be number of molecules, w\bic\b increases t\be frequency of collisions wit\b t\be walls of t\be container (D) An increase in t\be speed of t\be molecules t\bat t\ben collide wit\b t\be walls of t\be container wit\b greater force 30. As t\be reaction progresse s toward equilibrium, t\be rate of t\be forward reaction (A) increases until it becomes t\be same as t\be reverse reaction rate at equilibrium (B) stays constant before and after equilibrium is reac\bed (C) decreases to become a constant nonzero rate at equilibrium (D) decreases to become zero at equilibrium 31. If t\be decomposition reaction were to go to completion, t\be total pressure in t\be container would be (A) 1.4 atm (B) 2.0 atm (C) 2.8 atm (D) 3.0 atm
27 Chemistry Practice\5 Exam GO ON TO THE NEXT PAGE. 32. Which of the following statements about Kp, the equilib\bium constant fo\b the \beaction, is co\b\bect? (A) K p > 1 (B) K p 1, K p
Chemistry Practice\5 Exam 28 GO ON TO THE NEXT PAGE. Questions 34-38 K(s) + 1 2Cl 2(g ) Æ KCl(s) ∆H ° = −437 kJ/mol rxn The element\b K and Cl react directly to form the compound KCl according to the equation above. Refer to the information above and the table below to an\bwer the que\btion\b that follow. Proce\b\b D H ° (kJ/mol rxn ) K( s) → K(g ) v K( g) → K +(g ) + e − w Cl 2( g ) → 2 Cl(g ) x Cl(g) + e − → Cl −(g ) y K+( g ) + Cl −(g ) → KCl(s) z 34. How much heat i\b rele a\bed or ab\borbed when 0.050 mol of Cl 2( g ) i\b formed from KCl( s) ? (A) 87.4 kJ i\b relea\bed (B) 43.7 kJ i\b relea\bed (C) 43.7 kJ i\b ab\borbed (D) 87.4 kJ i\b ab\borbed 35. What remain\b in the r eaction ve\b\bel after equal ma\b\be\b of K( s) and Cl 2(g ) have reacted until either one or both of the reactant\b have been completely con\bumed? (A) KCl only (B) KCl and K only (C) KCl and Cl 2 only (D) KCl , K , and Cl 2 36. Which of the value\b of D H ∞ for a proce\b\b in the table i\b (are) le\b\b than zero (i.e., indicate(\b) an exothermic proce\b\b) ? (A) z only (B) y and z only (C) x, y, and z only (D) w, x, y, and z 37. It i\b ob\berved that the reaction producing KCl from it\b element\b goe\b e\b\bentially to completion. Which of the following i\b a true \btatement about the thermodynamic favorability of the reaction? (A) The reaction i\b favorable and driven by an enthalpy change only. (B) The reaction i\b unfavorable and driven by an entropy change only. (C) The reaction i\b favorable and driven by both enthalpy and entropy change\b. (D) The reaction i\b unfavorable due to both enthalpy and entropy change\b. Cl 2(g ) + 2 e − Æ 2 Cl −(g ) 38. Which of the following expre\b\bion\b i\b equivalent to DH ∞ for the reaction repre\bented above? (A) x + y (B) x - y (C) x + 2 y (D) 2 x y -
29 Chemistry Practice\5 Exam GO ON TO THE NEXT PAGE. 39. The experimental appara tus represented above is used to demonstrate the rates at whi\bh gases diffuse. When the \botton ba lls are pla\bed in the ends of a tube at the same time, the gases diffuse from ea\bh end and meet somewhere in between, where they rea\bt to form a white solid. Whi\bh of the following \bombinations will produ\be a solid \blosest to the \benter of the tube? (A) HCl and CH 3NH 2 (B) HCl and NH 3 (C) HBr and CH 3NH 2 (D) HBr and NH 3 40. Sili\bon \brystals are semi\bondu\btors. Whi\bh of the following is a \borre\bt reason for the in\brease in the \bondu\btivity of Si \brystals when a small fra\btion of Si atoms are repla\bed with those of a different element? (A) P atoms introdu\be additional mobile negative \bharges. (B) P atoms introdu\be additional mobile positive \bharges. (C) Ge atoms have more ele\btrons than Si atoms have. (D) Ge atoms are mu\bh smaller than Si atoms. 41. N 2 mole\bules absorb ultraviolet light but not visible light. I 2 mole\bules absorb both visible and ultraviolet light. Whi\bh of the following statements explains the observations? (A) More energy is required to make N2 mole\bules vibrate than is required to make I2 mole\bules vibrate. (B) More energy is required to remove an ele\btron from an I2 mole\bule than is required to remove an ele\btron from a N2 mole\bule. (C) Visible light does not produ\be transitions between ele\btroni\b energy levels in the N2 mole\bule but does produ\be transitions in the I2 mole\bule. (D) The mole\bular mass of I2 is greater than the mole\bular mass of N2 . Element Metalli\b Radius (pm) Melting Point ( ∞C) Common Oxidation State Au 144 1064 1+ , 3+ Cu 128 1085 1+ , 2+ Ag 144 961 1+ 42. To make Au stronger and harder, it is often alloyed with other metals, su\bh as Cu and Ag . Consider two alloys, one of Au and Cu and one of Au and Ag, ea\bh with the same mole fra\btion of Au . If the Au/Cu alloy is harder than the Au/Ag alloy, then whi\bh of the following is the best explanation based on the information in the table above? (A) Cu has two \bommon oxidation states, but Ag has only one. (B) Cu has a higher melting point than Au has, but Ag has a lower melting point than Au has. (C) Cu atoms are smaller than Ag atoms, thus they interfere more with the displa\bement of atoms in the alloy. (D) Cu atoms are less polarizable than are Au or Ag atoms, thus Cu has weaker interparti\ble for\bes.
Chemistry Practice\5 Exam 30 GO ON TO THE NEXT PAGE. 43. The photoelectron spectra a bove show the energy requ\bred to remove a 1 s electron from a n\btrogen atom and from an oxygen atom. Wh\bch of the follow\bng statements best accounts for the peak \bn the upper spectrum be\bng to the r\bght of the peak \bn the lower spectrum? (A) N\btrogen atoms have a half-f\blled p subshell. (B) There are more electron-electron repuls\bons \bn oxygen atoms than \bn n\btrogen atoms. (C) Electrons \bn the p subshell of oxygen atoms prov\bde more sh\beld\bng than electrons \bn the p subshell of n\btrogen atoms. (D) N\btrogen atoms have a smaller nuclear charge than oxygen atoms.
3\b Chemistry Practice\5 Exam GO ON TO THE NEXT PAGE. 44. Consider the molecules represented above and the data in the table below. Nonane and \b,3,4-trifluoropentane have almost id entical molar masses, but nonane has a significantly higher boiling point. Which of the following statements best helps explain this observation? (A) The C – F bond is easier to break than the C – H bond. (B) The C – F bond is more polar than the C – H bond. (C) The carbon chains are longer in nonane than they are in \b,3,4-trifluoropentane. (D) The carbon chains are farther apart in a sample of nonane than they are in \b,3,4-trifluoropentane. Compound Molecular Formula Molar Mass (g/mol) Boiling Point (°C) Nonane C 9H\b0 1\b8 151 \b,3,4-trifluoropentane C 5H9F3 1\b6 89
Chemistry Practice\5 Exam 32 GO ON TO THE NEXT PAGE. Questions 45-47 refer to galvanic cells made from different combinations of t\be t\bree \balf-cells described below. Half-cell 1: strip of Al(s) in 1.00 M Al(N\b 3)3(aq ) Half-cell 2: strip of Cu(s) in 1.00 M Cu(N\b 3)2(aq ) Half-cell 3: strip of Fe(s) in 1.00 M Fe(N\b 3)2(aq ) Galvanic Cell Half-cells Cell Reaction cellED (V) X 1 and 2 2 Al(s) + 3 Cu 2+(aq ) Æ 2 Al 3+(aq ) + 3 Cu( s) 2.00 Y 1 and 3 2 Al(s) + 3 Fe 2+(aq ) Æ 2 Al 3+(aq ) + 3 Fe(s) 1.22 Z 2 and 3 Fe(s) + Cu 2+(aq ) Æ Fe 2+(aq ) + Cu( s) ? 45. What is the standard cell potential of galvanic cell Z? (A) 0.26 V (B) 0.78 V (C) 2.34 V (D) 3.22 V 46. In galvanic cells Y and Z, which of the following takes place in half-cell 3 ? (A) Reduction occurs in both cell Y and cell Z. (B) \bxidation occurs in both cell Y and cell Z. (C) Reduction occurs in cell Y, and oxidation occurs in cell Z. (D) \bxidation occurs in cell Y, and reduction occurs in cell Z. 47. If the half-cell containing 1.00 M Fe(N\b 3)2(aq ) in galvanic cells Y and Z is replaced with a half-cell containing 5.00 M Fe(N\b 3)2(aq ), what will be the effect on the cell voltage of the two galvanic cells? (A) The voltage will increase in both cells. (B) The voltage will decrease in both cells. (C) The voltage will increase in cell Y and decrease in cell Z. (D) The voltage will decrease in cell Y and increase in cell Z.
33 Chemistry Practice\5 Exam GO ON TO THE NEXT PAGE. Questions 48-52 refer to the following. Concentration (M ) pH of Acid 1 pH of Acid 2 pH of Acid 3 pH of Acid 4 0.010 3.44 2.00 2.\b2 2.20 0.050 3.0\b 1.30 2.58 1.73 0.10 2.\b4 1.00 2.42 1.55 0.50 2.6\b 0.30 2.08 1.16 1.00 2.44 0.00 1.\b2 0.\b8 The pH of solutions of four acids prepared at various con centrations were measured and recorded in the table above. The four acids are, in no particular order, chlorous, hydrochloric, lactic, and propanoic. 48. For which acid is the value of the acid- dissociation constant, K a, the smallest? (A) Acid 1 (B) Acid 2 (C) Acid 3 (D) Acid 4 4\b. Which of the four acids listed in the table is hydrochloric acid? (A) Acid 1 (B) Acid 2 (C) Acid 3 (D) Acid 4 50. Of the following species, which has the greatest concentration in a 1.0 M solution of acid 1 at equilibrium? (A) OH − (B) H 3O+ (C) Acid 1 (D) The conjugate base of acid 1 51. If equal volumes of the four acids at a concentration of 0.50 M are each titrated with a strong base, which will require the greatest volume of base to reach the equivalence point? (A) Acid 1 (B) Acid 2 (C) Acid 3 (D) All the acids will require the same volume of base to reach the equivalence point. 52. A 25 mL sample of a 1.0 M solution of acid 1 is mixed with 25 mL of 0.50 M NaOH. Which of the following best explains what happens to the pH of the mixture when a few drops of 1.0 M HNO 3 are added? (A) The pH of the mixture increases sharply, because HNO 3 is a strong acid. (B) The pH of the mixture decreases sharply, because H3O+ ions were added. (C) The pH of the mixture stays about the same, because the conjugate base of acid 1 reacts with the added H3O+ ions. (D) The pH of the mixture stays about the same, because the OH − ions in the solution react with the added H3O+ ions.
Chemistry Practice\5 Exam 34
35 Chemistry Practice\5 Exam GO ON TO THE NEXT PAGE. NaF MgO Boiling Point ( ∞C) 1695 3600 Na + Mg \b + F− Cl − O \b− Ionic Radius (pm) 76 7\b 133 181 140 54. Based on the data in the tabl es above, which of the following statements provides the best prediction for the boiling point of NaCl ? (A) NaCl will have a lower boiling point than NaF because the coulombic attractions are weaker in NaCl than in NaF . (B) NaCl will have a boiling point between that of NaF and MgO because the covalent character of the bonds in NaCl is intermediate between that of MgO and NaF . (C) NaCl will have a higher boiling point than MgO because the ions are spaced farther apart in NaCl . (D) NaCl will have a higher boiling point than MgO because the energy required to transfer electrons from the anion to the cation is larger in NaCl than in MgO .
Chemistry Practice\5 Exam 36 GO ON TO THE NEXT PAGE. Acid Structure K a HNO 2 4.0 ¥10 −4 HC 3H5O2 1.3 ¥10 −5 HClO 3.0 ¥10 −8 HOC \bH5 1.\b ¥10 −10 55. The table above shows the values of Ka for four weak acids. Which of the following pairs of chemical species, when combined in equimolar amounts, results in a buffer with a pH closest to 7.5 ? (A) HNO 2 and OH − (B) HC 3H5O2 and C3H5O2− (C) HClO and ClO − (D) C \bH5OH and C\bH5O−
37 Chemistry Practice\5 Exam GO ON TO THE NEXT PAGE. 56. Beaker X and beaker Y each contain 1.0 L of \bolution, a\b \bhown above. A \btudent combine\b the \bolution\b by pouring them into a larger, previou\bly empty beaker Z and ob\berve\b the formation of a white precipitate. A\b\buming that volume\b are additive, which of the foll owing \bet\b of \bolution\b could be repre\bented by the diagram above? Beaker X Beaker Y Beaker Z (A) 2.0 M AgNO 3 2.0 M MgCl 2 4.0 M Mg(NO 3)2 and AgCl(s) (B) 2.0 M AgNO 3 2.0 M MgCl 2 2.0 M Mg(NO 3)2 and AgCl(s) (C) 2.0 M AgNO 3 1.0 M MgCl 2 1.0 M Mg(NO 3)2 and AgCl(s) (D) 2.0 M AgNO 3 1.0 M MgCl 2 0.50 M Mg(NO 3)2 and AgCl( s)
Chemistry Practice\5 Exam 38 GO ON TO THE NEXT PAGE. 2 N 2O5( g ) Æ 4 NO 2(g ) + O 2(g ) 57. A sample of N2O5 was placed \bn an evacuated conta\bner, and the reac t\bon represented above occurred. The value of 2 5N OP , the part\bal pressure of N2O5( g ), was measured dur\bng the react\bon and recorded \bn the table below. T\bme (m\bn) 2 5N OP (atm) ln( 2 5N OP ) 2 5N O 1 P (atm − 1) 0 150 5.0 0.0067 100 75 4.3 0.013 200 38 3.6 0.027 300 19 2.9 0.053 Wh\bch of the follow\bng correctly descr\bbes the react\bon? (A) The decompos\bt\bon of N 2O5 \bs a zero-order react\bon. (B) The decompos\bt\bon of N 2O5 \bs a f\brst-order react\bon. (C) The decompos\bt\bon of N 2O5 \bs a second-order react\bon. (D) The overall react\bon order \bs 3. Element Atom\bc Rad\bus F\brst Ion\bzat\bon Energy Calc\bum 194 pm 590 kJ/mol Potass\bum — — 58. Based on per\bod\bc trends and the data \bn the table above, wh\bch of the follow\bng are the most probable values of the atom\bc rad\bus and the f\brst \bon\bzat\bon energy for potass\bum, respect\bvely? (A) 242 pm, 633 kJ/mol (B) 242 pm, 419 kJ/mol (C) 120 pm, 633 kJ/mol (D) 120 pm, 419 kJ/mol
39 Chemistry Practice\5 Exam 59. The figure above shows that in solid hydrogen fluoride there are two different distan\bes between H atoms and F atoms. Whi\bh of the following best a\b\bounts for the two different distan\bes? (A) A\b\bommodation of the ne\bessary bond angles in the formation of the solid (B) Differen\be in strength between \bovalent bonds and intermole\bular attra\btions (C) Different isotopes of fluorine present in the samples (D) Uneven repulsions among nonbonding ele\btron pairs COCl 2( g ) Æ ¨ CO(g ) + Cl 2(g ) 60. COCl 2( g ) de\bomposes a\b\bording to the equation above. When pure COCl 2( g ) is inje\bted into a rigid, previously eva\buated flask at 690 K, the pressure in the flask is initially 1.0 atm. After the rea\btion rea\bhes equilibrium at 690 K, the total pressure in the flask is 1.2 atm. What is the value of Kp for the rea\btion at 690 K? (A) 0.040 (B) 0.050 (C) 0.80 (D) 1.0 S T O P IF YOU FINISH BEFORE TIME IS CALLED, YOU MAY CHECK YOUR WORK. DO NOT TURN TO SECTION II UNTIL YOU ARE TOLD TO DO SO
Chemistry Practice\5 Exam 40 DO NOT OPEN THIS BOOKLET UNTIL YOU ARE TOLD TO DO SO. At a Glance Total Tim\b90 minutes Numb\br of Qu\bstions7 P\brc\bnt of Total Scor\b50% Writing Instrum\bntEither pencil or pen with black or \bark blue ink El\bctronic D\bvic\bAllowe\b Instructions The questions are printed in this booklet.Pages containing a periodic table and lists containing equations and constants are also printed in this booklet . You may use the pages that the questions are printed on to organi\be your answers or for scratch work ,but you must write your answers in the areas designated for each response . Write clearly and legibly .Cross out any errors you make; erased or crossed -out work will not be scored .Manage your time carefully .Do not spend too much time on any one question . AP ® Chemistry Practice Exam SECTION II:Free Response Questions -
4\b Chemistry Practice\5 Exam
Chemistry Practice\5 Exam 42 GO ON TO THE NEXT PAGE. CHEMISTRY Section II 7 Constructed-Response \buestions (Time—90 minutes) YOU MAY USE YOUR CALCULATOR FOR SECTION II Directions: Questions 1, 2, and 3 are long constructed-re sponse questions that should require a\bout 20 minutes each to answer. Questions 4, 5, 6, and 7 are short constructed-response que stions that should require a\bout seven minutes each to answer. Read each question carefully and write your response in the space provided following each question. Your responses to these questions will \be scored on th e \basis of the accuracy and relevance of the information cited. Explanations should \be clear and well organized. Specific answer s are prefera\ble to \broad, diffuse responses. For calculations, clearly show the method used and the steps involved in arriving at your answers. It is to your advantage to do this, since you may o\btain partial credit if you do and you will receive little or no credit if you do not. 1. A student performs an experiment in which the conductivity of a solution of Ba(OH) 2 is monitored as the solution is titrated with 0.10 M H2SO 4. The original volume of the Ba(OH) 2 solution is 25.0 mL. A precipitate of BaSO 4 ( K sp = 1.0 × 10 − 10 ) formed during the titration. The data collect ed from the experiment are plotted in the graph a\bove. (a) As the first 30.0 mL of 0.10 M H2SO 4 are added to the Ba(OH) 2 solution, two types of chemical reactions occur simultaneously. On the lines provided \below, wr ite the \balanced net-ionic equations for (i) the neutralization reaction and (ii) the precipitation reaction. (i) Equation for neutralization reaction: ___________________________________________________ (ii) Equation for precipitation reaction: ____________________________________________________
43 Chemistry Practice\5 Exam GO ON TO THE NEXT PAGE. (b) The conductivity of the Ba(OH) 2 so\bution decreases as the vo\bume of added 0.10 M H 2SO 4 changes from 0.0 mL to 30.0 mL. (i) Identify the chemica\b species th at enab\be the so\bution to conduct e\bectricity as the first 30.0 mL of 0.10 M H2SO 4 are added. (ii) On the basis of the equations you wrote in part (a), exp\bain why the conductivity decreases. (c) Using the information in the graph, ca\bcu\bate the mo\barity of the origina\b Ba(OH) 2 so\bution. (d) Ca\bcu\bate the concentration of Ba 2+( aq ) in the so\bution at the equiva\bence point (after exact\by 30.0 mL of 0.10 M H2SO 4 are added). (e) The concentration of Ba 2+( aq ) in the so\bution decreases as the vo\bume of added 0.10 M H 2SO 4 increases from 30.0 mL to 31.0 mL. Exp\bain.
Chemistry Practice\5 Exam 44 GO ON TO THE NEXT PAGE. ADDITIONAL PAGE FOR ANSWERING QUESTION 1
45 Chemistry Practice\5 Exam GO ON TO THE NEXT PAGE. ADDITIONAL PAGE FOR ANSWERING QUESTION 1
Chemistry Practice\5 Exam 46 GO ON TO THE NEXT PAGE. 2. A student is given the task of determining the enthalpy of rea\btion for the rea\btion between HCl( aq) and NaOH( aq) . The following materials are available. 1.00 M HCl(aq) 1.00 M NaOH( aq) distilled water 2.00 M HCl(aq ) 2.00 M NaOH(aq ) goggles insulated \bups with \bovers gloves lab \boat thermometer (± 0.1°C) stirring rod The student may sele\bt from the glassware listed in the table below. Glassware Items Pre\bision 250 mL Erlenmeyer flasks ± 25 mL 100 mL beakers ± 10 mL 100 mL graduated \bylinders ± 0.1 mL (a) The student sele\bts two 100 mL beakers, uses them to measure 50 mL ea\bh of 1.00 M HCl(aq) solution and 1.00 M NaOH( aq) solution, and measures an initial temperat ure of 24.5°C for ea\bh solution. Then the student pours the two solutions into an insulated \bup, stirs the mixture, \bovers the \bup, and re\bords a maximum temperature of 29.9°C. (i) Is the experimental design suffi\bient to determine the enthalpy of rea\btion to a pre\bision of two signifi\bant figures? Justify your answer. (ii) List two spe\bifi\b \bhanges to the experiment th at will allow the student to determine the enthalpy of rea\btion to a pre\bision of three signifi\bant figures. Explain. (b) A se\bond student is given two solutions, 75.0 mL of 1.00 M HCl and 75.0 mL of 1.00 M NaOH, ea\bh at 25.0 °C. The student pours the solutions into an insulated \bup, stirs the mixture, \bovers the \bup, and re\bords the maximum temperature of the mixture. (i) The student \bal\bulates the amount of heat evolve d in the experiment to be 4.1 kJ. Cal\bulate the student’s experimental value for th e enthalpy of rea\btion, in kJ/mol rxn . (ii) The student assumes that the thermometer and the \balorimeter do not absorb energy during the rea\btion. Does this assumption result in a \bal\bulate d value of the enthalpy of rea\btion that is higher than, lower than, or the same as it would have b een had the heat \bapa\bities of the thermometer and \balorimeter been taken into a\b\bount? Justify your answer. (iii) One assumption in interpreting the results of the experiment is that the rea\btion between HCl(aq) and NaOH( aq) goes to \bompletion. Justify the validity of th is assumption in terms of the equilibrium \bonstant for the rea\btion. (\b) A third student \bal\bulates a value for the enthalpy of rea\btion that is signifi\bantly higher than the a\b\bepted value. (i) Identify a spe\bifi\b error in pro\bedure made by the student that will result in a \bal\bulated value for the enthalpy of rea\btion that is higher than the a\b\bepted value. (Vague statements like “human error” or “in\borre\bt \bal\bulations” will not earn \bredit.) (ii) Explain how the error that you identified in part (\b)(i) leads to a \bal\bulated value for the enthalpy of rea\btion that is higher than the a\b\bepted value.
47 Chemistry Practice\5 Exam GO ON TO THE NEXT PAGE. ADDITIONAL PAGE FOR ANSWERING QUESTION 2
Chemistry Practice\5 Exam 48 GO ON TO THE NEXT PAGE. ADDITIONAL PAGE FOR ANSWERING QUESTION 2
49 Chemistry Practice\5 Exam GO ON TO THE NEXT PAGE. ADDITIONAL PAGE FOR ANSWERING QUESTION 2
Chemistry Practice\5 Exam 50 GO ON TO THE NEXT PAGE. SO 2Cl 2(g ) Æ ¨ SO 2( g ) + Cl 2(g ) 3. A 4.32 g sample of liq\bid SO 2Cl 2 is placed in a rigid, evac\bated 1.50 L reaction vessel. As the container is heated to 400. K, the sample vaporizes completely and starts to decompose according to the eq\bation above. The decomposition reaction is endothermic. (a) If no decomposition occ\brred, what wo\bld be the press\bre, in atm, of the SO 2Cl 2( g ) in the vessel at 400. K ? (b) When the system has reached eq\b ilibri\bm at 400. K, the total press\bre in the container is 1.26 atm. Calc\blate the partial press\bres, in atm, of SO 2Cl 2( g ) , SO 2(g ) , and Cl 2(g ) in the container at 400. K. (c) For the decomposition reaction at 400. K , (i) write the eq\bilibri\bm-constant expression for Kp for the reaction, and (ii) calc\blate the val\be of the eq\bilibri\bm constant, Kp. (d) The temperat\bre of the eq\bilibri\bm mixt\br e is increased to 425 K . Will the val\be of Kp increase, decrease, or remain the same? J\bstify yo\br prediction. (e) In another experiment, the original partial press\bres of SO 2Cl 2( g ) , SO 2(g ) , and Cl 2(g ) are 1.0 atm each at 400. K . Predict whether the amo\bnt of SO 2Cl 2( g ) in the container will increase, decrease, or remain the same. J\bstify yo\br prediction.
. . . . . .