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AP ® Chemistry Practice Exam From the 2 015 Administration NOT E: This is a modified version of the 201 5 AP Chemistry Exam. This Practic e Exa m is provided by the Colleg e Boar d fo r AP Exam preparation . Teacher s ar e permitted to download the material s an d mak e copies to use wit h thei r student s in a classroo m settin g onl y. T o maintai n th e securit y of this exam , teacher s shoul d collec t al l material s afte r thei r administratio n an d keep the m in a secure location . Exam s ma y no t be poste d on schoo l or personal websites, no r electronically redistributed for an y reason. Fu rther distributio n of thes e material s outside of the secur e Colleg e Board sit e disadvantages teacher s wh o rel y on uncirculated questions for classroo m testing . An y additional distribution is in violation of the Colleg e Board ’s copyright policies an d ma y resul t in the terminatio n of Practic e Exa m acces s fo r you r schoo l as well as the removal of access to other online services such as the A P Teache r Communit y an d Onlin e Scor e Repo rts.
Contents Exam Instructions Student Answer Sheet for the Multiple -Choice Section Section I: Multiple -Choice Questions Section II: Free -Response Questions Multiple -Choice Answer Key Free- Response Scoring Guidelines Scoring Worksheet Note: This publication shows the page numbers that appeared in the 201 4−15 AP Exam Instructions book and in th e actual exam. This publication was not repaginated to begin with page 1. © 2015 The College Board. College Board, Advanced Placement Program, AP, SAT and the acorn logo are registered trademarks of the College Board. All other products and services may be trademarks of their respective owners. Permission to use copyrighted College Board materials may be requested online at: ww w.collegeboard.com/inquiry/cbpermit.html.
Exam Instructions The following contains instructions taken from the 2014−15 AP Exam Instructions book.
42 What Proctors Need to Bring to This Exam • Exam packets • Answer sheets • AP St udent Packs • 201 4 - 15 AP Coordinator’s Manual • This boo k — AP Exam Instructions • AP Ex am Seating Chart template(s) • Sch ool Code and Home-School/Self- Study Codes • Ext ra calculators • Penc il sharpener • Con tainer for students’ electronic devices (if needed) • Ext ra No . 2 pencils with erasers • Ext ra pens with black or dark blue ink • Ext ra paper • St apler • Wa t c h • Sig ns for the door to the testing room – “E xam in Progress” – “C ell phones are prohibited in the testing room” Note: Tables of equations and constants are provided in the exam booklets for both sections of the exam . Students are not allowed to use calculators in Section I of the AP Chemistry Exam . However, students are permitted to use four-function, scientific, or graphing calculators to answer questions in Section II . Before starting the exam administration, make sure that each student has an appropriate calculator and that any student with a graphing calculator has a model from the approved list on page 46 of the 2014 - 15 AP Coordinator’s Manual . See pages 43–46 of the 2014 - 15 AP Coordinator’s Manual for more information . If a student does not have an appropriate calculator or has a graphing calculator not on the approved list, you may provide one from your supply . If the student does not want to use the calculator you provide, or does not want to use a calculator at all, he or she must hand copy, date, and sign the release statement on page 44 of the 2014 - 15 AP Coordinator’s Manual . AP® Chemistry Exam Regularly Scheduled Exam Date: Monday morning, May 4, 2015 Late-Testing Exam Date: Thursday afternoon, May 21, 2015 Section I Total Time: 1 hr. 30 min. Section II Total Time: 1 hr. 45 min. Section I Total Time: 1 hour 30 minutes Calculator not permitted P ercent of Total Score: 50% Writing Instrument: Pencil required Number of Questions: 60 * *The number of questions may vary slightly depending on the form of the exam. Section II Total Time: 1 hour 45 minutes Calculators allowed for all of Section II Percent of Total Score: 50% Writing Instrument: Either pencil or pen with black or dark blue ink Number of Questions: 7 (3 ten-point and 4 four-point questions; 105 minutes) ? 2015 The College Board. Visit the College Board on the Web: www.collegeboard.org.
43 During the administration of Section II students may have no more than two calculators on their desks . Calculators may not be shared . Calculator memories do not need to be cleared before or after the exam . Students with Hewlett-Packard 48–50 Series and Casio FX-9860 graphing calculators may use cards designed for use with these calculators . Proctors should make sure infrared ports (Hewlett-Packard) are not facing each other . Since graphing calculators can be used to store data, including text, proctors should monitor that students are using their calculators appropriately. Attempts by students to use the calculator to remove exam questions and/or answers from the room may result in the cancellation of AP Exam scores. Students will be allowed to use the table of equations and constants on both sections of the exam . SECTION I: Multiple Choice ! Do not begin the exam instructions below until you have completed the appropriate General Instructions for your group. Make sure you begin the exam at the designated time . Remember: You must complete a seating chart for this exam . See pages 279–280 for a seating chart template and instructions . See the 2014-15 AP Coordinator’s Manual for exam seating requirements (pages 48–50, 88) . If you are giving the regularly scheduled exam, say: It is Monday morning, May 4, and you will be taking the AP Chemistry Exam. If you are giving the alternate exam for late testing, say: It is Thursday afternoon, May 21, and you will be taking the AP Chemistry Exam. In a moment, you will open the packet that contains your exam materials. By opening this packet, you agree to all of the AP Program’s policies and procedures outlined in the 2014 - 15 Bulletin for AP Students and Parents . You may now remove the shrinkwrap from your exam packet and take out the Section I booklet, but do not open the booklet or the shrinkwrapped Section II materials. Put the white seals aside. . . . Carefully remove the AP Exam label found near the top left of your exam booklet cover. Now place it on page 1 of your answer sheet on the light blue box near the top right-hand corner that reads “AP Exam Label.” If students accidentally place the exam label in the space for the number label or vice versa, advise them to leave the labels in place . They should not try to remove the label; their exam will be processed correctly . Read the statements on the front cover of Section I and look up when you have finished. . . . Sign your name, and write today’s date. Look up when you have finished. . . . Now print your full legal name where indicated. Are there any questions? . . . Turn to the back cover and read it completely. Look up when you have finished. . . . AP Exam Instructions CHEMISTRY ? 2015 The College Board. Visit the College Board on the Web: www.col\ legeboard.org.
44 Chemistry Are there any questions? . . . You will now take the multiple-choice portion of the exam. You should have in front of you the multiple-choice booklet and your answer sheet. You may never discuss these specific multiple-choice questions at any time in any form with anyone, including your teacher and other students. If you disclose these questions through any means, your AP Exam score will be canceled. . . . You must complete the answer sheet using a No. 2 pencil only. Mark all of your responses beginning on page 2 of your answer sheet, one response per question. Completely fill in the circles. If you need to erase, do so carefully and completely. No credit will be given for anything written in the exam booklet. Scratch paper is not allowed, but you may use the margins or any blank space in the exam booklet for scratch work. Calculators are not allowed for this section. Please put your calculators under your chair. Are there any questions? . . . You have 1 hour and 30 minutes for this section. Open your Section I booklet and begin. 126 3 9 Note Start Time here . Note Stop Time here . Check that students are marking their answers in pencil on their answer sheets, and that they are not looking at their shrinkwrapped Section II booklets . After 1 hour and 20 minutes, say: There are 10 minutes remaining. After 10 minutes, say: Stop working. Close your booklet and put your answer sheet on your desk, face up. Make sure you have your AP number label and an AP Exam label on page 1 of your answer sheet. Sit quietly while I collect your answer sheets. Collect an answer sheet from each student . Check that each answer sheet has an AP number label and an AP Exam label . After all answer sheets have been collected, say: Now you must seal your exam booklet using the white seals you set aside earlier. Remove the white seals from the backing and press one on each area of your exam booklet cover marked “PLACE SEAL HERE.” Fold each seal over the back cover. When you have finished, place the booklet on your desk, face up. I will now collect your Section I booklet. . . . Collect a Section I booklet from each student . Check that each student has signed the front cover of the sealed Section I booklet . There is a 10-minute break between Sections I and II . When all Section I materials have been collected and accounted for and you are ready for the break, say: Please listen carefully to these instructions before we take a 10-minute break. All items you placed under your chair at the beginning of this exam must stay there, and you are not permitted to open or access them in any way. Leave your shrinkwrapped Section II packet on top of your desk during the break. You are not allowed to consult teachers, other students, or textbooks during the break. You may not make phone calls, send text messages, check email, use a social networking site, or access any electronic ? 2015 The College Board. Visit the College Board on the Web: www.collegeboard.org.
45 or communication device. Remember, you may never discuss the multiple- choice questions at any time in any form with anyone, including your teacher and other students. If you disclose these questions through any means, your AP Exam score will be canceled. Are there any questions? . . . 126 3 9 You may begin your break. Testing will resume at . SECTION II: Free Response After the break, say: May I have everyone’s attention? Place your Student Pack on your desk. . . . You may now remove the shrinkwrap from the Section II packet, but do not open the exam booklet until you are told to do so. . . . Read the bulleted statements on the front cover of the exam booklet. Look up when you have finished. . . . Now place an AP number label on the shaded box. If you don’t have any AP number labels, write your AP number in the box. Look up when you have finished. . . . Read the last statement. . . . Using your pen, print the first, middle and last initials of your legal name in the boxes and print today’s date where indicated. This constitutes your signature and your agreement to the statements on the front cover. . . . Turn to the back cover and complete Item 1 under “Important Identification Information.” Print the first two letters of your last name and the first letter of your first name in the boxes. Look up when you have finished. . . . In Item 2, print your date of birth in the boxes. . . . In Item 3, write the school code you printed on the front of your Student Pack in the boxes. . . . Read Item 4. . . . Are there any questions? . . . I need to collect the Student Pack from anyone who will be taking another AP Exam. You may keep it only if you are not taking any other AP Exams this year. If you have no other AP Exams to take, place your Student Pack under your chair now. . . . While Student Packs are being collected, read the information on the back cover of the exam booklet. Do not open the exam booklet until you are told to do so. Look up when you have finished. . . . Collect the Student Packs . Then say: Are there any questions? . . . AP Exam Instructions CHEMISTRY ? 2015 The College Board. Visit the College Board on the Web: www.collegeboard.org.
46 Chemistry Calculators may be used for Section II. You may get your calculators from under your chair and place them on your desk. . . . You have 1 hour and 45 minutes to complete Section II. You are responsible f or pacing yourself, and you may proceed freely from one question to the next. You must write your answers in the exam booklet using a pen with black or dark blue ink or a No. 2 pencil. If you use a pencil, be sure that your writing is dark enough to be easily read. If you need more paper during the exam, raise your hand. At the top of each extra sheet of paper you use, be sure to write only your AP number and the number of the question you are working on. Do not write your name. Are there any questions? . . . You may begin. 12 6 3 9 Note Start Time here . Note Stop Time here . Proctors should also make sure that Hewlett-Packard calculators’ infrared ports are not facing each other and that students are not sharing calculators . After 1 hour and 35 minutes, say: There are 10 minutes remaining. After 10 minutes, say: Stop working and close your exam booklet. Place it on your desk, face up. . . . If any students used extra paper for the free-response section, have those students staple the extra sheet(s) to the first page corresponding to that question in their exam booklets . Complete an Incident Report and include any exam booklets with extra sheets of paper in an Incident Report return envelope (see page 57 of the AP Coordinator’s Manual for details) . Then say: Remain in your seat, without talking, while the exam materials are collected. . . . Collect a Section II booklet from each student . Check for the following: • Exam booklet front cover: The student placed an AP number label on the shaded box, and printed his or her initials and today’s date . • E xam booklet back cover: The student completed the “Important Identification Information” area . When all exam materials have been collected and accounted for, return to students any electronic devices you may have collected before the start of the exam . If you are giving the regularly scheduled exam, say: You may not discuss or share these specific free-response questions with anyone unless they are released on the College Board website in about two days. Your AP Exam score results will be available online in July. If you are giving the alternate exam for late testing, say: None of the questions in this exam may ever be discussed or shared in any way at any time. Your AP Exam score results will be available online in July. ? 2015 The College Board. Visit the College Board on the Web: www.collegeboard.org.
47 If any students completed the AP number card at the beginning of this exam, say: Please remember to take your AP number card with you. You will need the information on this card to view your scores and order AP score reporting services online. Then say: You are now dismissed. All exam materials must be placed in secure storage until they are returned to the AP Program after your school’s last administration . Before storing materials, check the “School Use Only” section on page 1 of the answer sheet and: • Fill in the appropriate section number circle in order to access a separate AP Instructional Planning Report (for regularly scheduled exams only) or subject score roster at the class section or teacher level . See “Post-Exam Activities” in the 2014 - 15 AP Coordinator’s Manual . • C heck your list of students who are eligible for fee reductions and fill in the appropriate circle on their registration answer sheets . Be sure to give the completed seating chart to the AP Coordinator . Schools must retain seating charts for at least six months (unless the state or district requires that they be retained for a longer period of time) . Schools should not return any seating charts in their exam shipments unless they are required as part of an Incident Report . AP Exam Instructions CHEMISTRY ? 2015 The College Board. Visit the College Board on the Web: www.collegeboard.org.
Student Answer Sheet for the Multiple -Choice Section Use this section to capture student responses. (Note that the following answer sheet is a sample, and may differ from one used in an actual exam. )
Sign your legal name as it will appear on your college applications. Date To maintain the security of the exam and the validity of my AP score, I w\ ill allow no one else to see the multiple-choice questions. I will seal the multiple-choice booklet when asked to do so, and I will not dis\ cuss these questions with anyone at any time after completing the section. I am aware of and agree to the AP Program’s policies and procedures as outlined in the 2014-15 Bulletin for AP Students and Parents, including using testing accommodations (e.g., extended time, computer\ , etc.) only if I have been preapproved by College Board Services for Students with Disabilities.COMPLETE THIS AREA AT EVERY EXAM.USE NO. 2 PENCIL ONLY A. SIGNATURE PAGE 1 AP Exam Label (from Section I Booklet) AP Number Label (from Student Pack) Answer Sheet 2 015 B. LEGAL NAME Omit apostrophes, Jr., II. Legal First Name ? First 12 Letters Legal Last Name ? First 15 Letters MI A A A A A A A A A A A A A A A B B B B B B B B B B B B B B B C C C C C C C C C C C C C C C D D D D D D D D D D D D D D D E E E E E E E E E E E E E E E F F F F F F F F F F F F F F F G G G G G G G G G G G G G G G H H H H H H H H H H H H H H H I I I I I I I I I I I I I I I J J J J J J J J J J J J J J J K K K K K K K K K K K K K K K L L L L L L L L L L L L L L L M M M M M M M M M M M M M M M N N N N N N N N N N N N N N N O O O O O O O O O O O O O O O P P P P P P P P P P P P P P P Q Q Q Q Q Q Q Q Q Q Q Q Q Q Q R R R R R R R R R R R R R R R S S S S S S S S S S S S S S S T T T T T T T T T T T T T T T U U U U U U U U U U U U U U U V V V V V V V V V V V V V V V W W W W W W W W W W W W W W W X X X X X X X X X X X X X X X Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z – – – – – – – – – – – – – 1 2 3 4 5 6 7 8 9 A A A A A A A A A A A A A B B B B B B B B B B B B B C C C C C C C C C C C C C D D D D D D D D D D D D D E E E E E E E E E E E E E F F F F F F F F F F F F F G G G G G G G G G G G G G H H H H H H H H H H H H H I I I I I I I I I I I I I J J J J J J J J J J J J J K K K K K K K K K K K K K L L L L L L L L L L L L L M M M M M M M M M M M M M N N N N N N N N N N N N N O O O O O O O O O O O O O P P P P P P P P P P P P P Q Q Q Q Q Q Q Q Q Q Q Q Q R R R R R R R R R R R R R S S S S S S S S S S S S S T T T T T T T T T T T T T U U U U U U U U U U U U U V V V V V V V V V V V V V W W W W W W W W W W W W W X X X X X X X X X X X X X Y Y Y Y Y Y Y Y Y Y Y Y Y Z Z Z Z Z Z Z Z Z Z Z Z Z – – – – – – – – – – 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 4 4 4 4 4 4 4 4 5 5 5 5 5 5 5 5 6 6 6 6 6 6 6 6 7 7 7 7 7 7 7 7 8 8 8 8 8 8 8 8 9 9 9 9 9 9 9 9 0 0 1 1 2 2 3 3 4 5 6 7 8 9 6 12 7 1 8 2 9 3 10 4 11 5 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 4 4 4 4 4 4 4 4 4 4 5 5 5 5 5 5 5 5 5 5 6 6 6 6 6 6 6 6 6 6 7 7 7 7 7 7 7 7 7 7 8 8 8 8 8 8 8 8 8 8 9 9 9 9 9 9 9 9 9 9 S D. EXAM DATE C. YOUR AP NUMBER Month AM PM F. MULTIPLE-CHOICE BOOKLET SERIAL NUMBER H. AP EXAM I AM TAKING USING THIS ANSWER SHEET Exam Name: Form Code: Form: COMPLETE THIS AREA ONLY ONCE. SCHOOL USE ONLY Fee Reduction Granted Section Number Option 1 Option 2 E. EXAM START TIME 0 0 1 1 2 3 4 5 6 7 8 9 1 2 0 0 0 1 1 1 2 2 2 3 3 3 4 4 4 5 5 5 6 6 6 7 7 7 8 8 8 9 9 9 G. ONLINE PROVIDER CODE Day 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 4 4 4 4 4 4 4 4 4 5 5 5 5 5 5 5 5 5 6 6 6 6 6 6 6 6 6 7 7 7 7 7 7 7 7 7 8 8 8 8 8 8 8 8 8 9 9 9 9 9 9 9 9 9 L. SOCIAL SECURITY NUMBER (Optional) 104246-00657• UNLWEB315 Q3914/1- 4 COLLEGE CODE 0 0 0 0 1 1 1 1 2 2 2 2 3 3 3 3 4 4 4 4 5 5 5 5 6 6 6 6 7 7 7 7 8 8 8 8 9 9 9 9 M. COLLEGE TO RECEIVE YOUR AP SCORE REPORT College Name State Country Using the college code listed in the AP Student Pack, indicate the ONE college that you want to receive your AP score report. City SCHOOL CODE 0 0 0 0 0 0 1 1 1 1 1 1 2 2 2 2 2 2 3 3 3 3 3 3 4 4 4 4 4 4 5 5 5 5 5 5 6 6 6 6 6 6 7 7 7 7 7 7 8 8 8 8 8 8 9 9 9 9 9 9 School Name State Country J. SCHOOL YOU ATTEND City 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 4 4 4 4 4 4 4 4 4 4 5 5 5 5 5 5 5 5 5 5 6 6 6 6 6 6 6 6 6 6 7 7 7 7 7 7 7 7 7 7 8 8 8 8 8 8 8 8 8 8 9 9 9 9 9 9 9 9 9 9 INTERNATIONAL PHONE I. AREA CODE AND PHONE NUMBER 0 0 0 0 1 1 1 1 2 2 2 2 3 3 3 3 4 4 4 5 5 5 6 6 6 7 7 7 8 8 8 9 9 9 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month DayYear K. DATE OF BIRTH N. CURRENT GRADE LEVEL Not yet in 9th grade 9th 10th 11th 12th No longer in high school B123456789T 779934
P. LANGUAGE — Do not complete this section unless instructed to do so. 1 2 34 5 67 8 9 A B C D E F G H I A B C D E F G H I A B C D E F G H I A B C D E F G H I A B C D E F G H I A B C D E F G H I A B C D E F G H I A B C D E F G H I A B C D E F G H I If this answer sheet is for the French Language and Culture, German Language and Culture, Italian Language and Culture, Spanish Language and Culture, or Spanish Literature and Culture Exam, please answer the following questions. Your responses will not affect your score. 1. Have you lived or studied for one month or more in a country where the language of the exam you are now taking is spoken? Yes No DO NOT WRITE IN THIS AREA O. SURVEY QUESTIONS — Answer the survey questions in the AP Student Pack. Do not put responses to exam questions in this section. PAGE 2 COMPLETE THIS AREA AT EACH EXAM (IF APPLICABLE). Indicate your answers to the exam questions in this section (pages 2 and 3). Mark only one response per question for Questions 1 through 120. If a question has only four answer options, do not mark option E. Answers written in the multiple-choice booklet will not be scored. A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 5051 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 QUESTIONS 1–75 Yes No 2. Do you regularly speak or hear the language at home? A B C D A B C D You must use a No. 2 pencil and marks must be complete. Do not use a mechanical pencil. It is very important that you fill in the entire circle darkly and completely. If you change your response, erase as completely as possible. Incomplete marks or erasures may affect your score. COMPLETE MARK EXAMPLES OF INCOMPLETE MARKS SELECTED MEDIA EXAMS R W O OTHER EXAMS R W O PT02 TOTAL PT03 Subscore (if applicable) PT04 Subscore (if applicable) ETS USE ONLY Exam Exam 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9
/ / / – . . . . . 0 0 0 0 1 1 1 1 1 2 2 2 2 2 3 3 3 3 3 4 4 4 4 4 5 5 5 5 5 6 6 6 6 6 7 7 7 7 7 8 8 8 8 8 9 9 9 9 9 / / / – . . . . . 0 0 0 0 1 1 1 1 1 2 2 2 2 2 3 3 3 3 3 4 4 4 4 4 5 5 5 5 5 6 6 6 6 6 7 7 7 7 7 8 8 8 8 8 9 9 9 9 9 / / / – . . . . . 0 0 0 0 1 1 1 1 1 2 2 2 2 2 3 3 3 3 3 4 4 4 4 4 5 5 5 5 5 6 6 6 6 6 7 7 7 7 7 8 8 8 8 8 9 9 9 9 9 / / / – . . . . . 0 0 0 0 1 1 1 1 1 2 2 2 2 2 3 3 3 3 3 4 4 4 4 4 5 5 5 5 5 6 6 6 6 6 7 7 7 7 7 8 8 8 8 8 9 9 9 9 9 / / / – . . . . . 0 0 0 0 1 1 1 1 1 2 2 2 2 2 3 3 3 3 3 4 4 4 4 4 5 5 5 5 5 6 6 6 6 6 7 7 7 7 7 8 8 8 8 8 9 9 9 9 9 For Students Taking AP Biology / / / – . . . . . 0 0 0 0 1 1 1 1 1 2 2 2 2 2 3 3 3 3 3 4 4 4 4 4 5 5 5 5 5 6 6 6 6 6 7 7 7 7 7 8 8 8 8 8 9 9 9 9 9 121123 122 124125 126 Write your answer in the boxes at the top of the griddable area and fill in the corresponding circles. Mark only one circle in any column. You will receive credit only if the circles are filled in correctly. PAGE 3 DO NOT WRITE IN THIS AREA A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E A B C D E 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 10 0 101 10 2 10 3 10 4 10 5 10 6 10 7 10 8 10 9 110111 11 2 11 3 11 4 11 5 11 6 11 7 11 8 11 9 120 Be sure each mark is dark and completely fills the circle. If a question has only four answer options, do not mark option E. QUESTIONS 76–120 © 2014 The College Board. College Board, AP, Student Search Service and the acorn logo are registered trademarks of the College Board. QUESTIONS 121–126 A B C D A B C D A B C D A B C D A B C D A B C D A B C D A B C D A B C D A B C D A B C D A B C D 131 132 133 134 135 136 137 138139 140 141 142 For Students Taking AP Physics 1 or AP Physics 2 Mark two responses per question. You will receive credit only if both correct responses are selected. QUESTIONS 131–142
X. ETHNICITY/RACE COMPLETE THIS AREA ONLY ONCE. 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YOUR MAILING ADDRESS Use the address abbreviations from your AP Student Pack. Fill in only one circle per column. Indicate a space in your address by leaving a blank box; do not grid that column. AK AL AR AZ CA CO CT DC DE FL GA HI IA ID IL IN KS KY LA MA MD MEMI MN MO MS MT NC ND NE NH NJ NM NV NY OH OK OR PA RI SC SD TN TX UT VAVT WA WI WV WY Puerto Rico AA AE AP Other S TAT E R. FOR STUDENTS OUTSIDE THE UNITED STATES ONLY T. EMAIL ADDRESS If your address does not fit in the spaces provided in Item Q, fill in as many circles as you can, then fill in the circle in Item R and print the remainder of your address in the spaces provided. Address City State or Province Country ZIP or Postal Code By providing your email address, you are granting the College Board permission to use your email in accordance with the policies in the 2014-15 Bulletin for AP Students and Parents. S. STUDENT IDENTIFIER (Student ID Number) U. 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Section I: Multiple-Choice Questions This is the multiple-choice section of the 201 5 AP exam. It includes cover material and other administrative instructions to help familiarize students with the mechanics of the exam. (Note that future exams may differ in look from the following content.) For purposes of test security and/or statistical analysis, some questions have been removed from the version of the exam that was administered in 2015. Therefore, t he timing indicated here may not be appropriate for a practice exam.
AP ® Chemistry Exam SECTION I: Multiple Choice 2015 DO NOT OPEN THIS BOOKLET UNTIL YOU ARE TOLD TO DO SO. At a Glance Total Time 1 hour, 30 minutes Number of Questions 50 Percent of Total Score 50% Writing Instrument Pencil required Electronic Device None allowed Instructions Section I of this exam contains 50 multiple -choice questions . Fill in only the circles for numbers 1 through 50 on your answer sheet. Pages containing a periodic table and lists containing equations and constants are also printed in this booklet . 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. Afer you have decided which of the suggested answers is best , completely fll in the corresponding circle on the answer sheet. Because this section ofers only four answer options for each question , do not mark the ( E ) answer circle for any question . 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 efectively , 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 Section I is based only on the number of questions answered correctly. Points are not deducted for incorrect answers or unanswered questions. Form I Form Code 4LBP4-S 25
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L, mL = liter(s), milliliter(s) mm Hg = millimeters of mercury g = gram(s) E = h c = = frequency Planck’s constant, h = 6.626 10 34 Js Speed of light, c = 2.998 10 8 ms 1 Avogadro’s number = 6.022 10 23 mol 1 Electron charge, e = 1.602 × 10 19 coulomb K c = [C] [D] [A] [B] c d a b , where a A + b B c C + d D K p = C D A B () ( ) () ( ) c d a b P P P P K a = [H ][A ] [HA] + - K b = [OH ][HB ] [B] - + K w = [H +][OH ] = 1.0 10 14 at 25 C = K a K b 灈‽⁰ K a + log [A ] [HA] - Kc (molar concentrations) K w (water) ln[A]t ln[A] 0 = kt [] [] 0 A A 1 1 t - = kt t ½ = 0.693 k t ½ = half-life AP ® CHEMISTRY EQUATION S AND CONSTANTS Throughout the exam the following symbols have th e definitions specified unless otherwise noted. J, kJ = joule(s), kilojoule(s) nm = nanometer(s) V = volt(s) atm = atmosphere(s) mol = mole(s) ATOMIC STRUCTURE E = energy = wavelength EQUILIBRIUM pH = log [H +] , pOH = log [OH ] 14 = pH + pOH p K a = log K a , pK b = log K b Equilibrium Constants K p (gas pressures) K a (weak acid) K b (weak base) KINETICS k = rate constant t = time -3-
1 atm = 760 mm Hg = 760 torr PV = nRT 浯汥猠䄠 PA = P total X A, where X A = total moles = P A + P B + P C + . . . P total m n = M K = C + 273 D = m V 1 2 KE per molecule = mv 2 A = abc M = molar mass KE = kinetic energy A = absorbance R = 8.314 J mol 1K1 = 62.36 L torr mol 1K1 S = Â S products - Â S reactants H = Â D H f products - Â DH f reactants G = Â D G f products - Â DG reactants f G = H TS = RT ln K = nF E q I = t S = standard entropy H = standard enthalpy G = standard Gibbs free ener gy E = standard reduction potential F = 96,485 coulombs per mole of electrons Faraday’s constant, ㄠ橯畬e ㄠ癯汴 㴠 ㄠ捯畬潭戠 GASES, LIQUIDS, AND SOLUTIONS Molarity, M = moles of solute per liter of solution THERMODYNAMICS / ELECTROCHEMISTRY q = mcT P = pressure V = volume T = temperature n = number of moles m = mass D = density v = velocity a = molar absorptivity b = path length c = concentratio n Gas constant, = 0.08206 L atm mol 1K1 STP = 273.15 K and 1.0 atm Ideal gas at STP = 22.4 L mol −1 q = heat m = mass c = specific heat capacity T = temperature n = number of moles I = current (amperes) q = charge (coulombs) t = time (seconds) -4-
and a 0.5 mol sample He( g) or Ne( g) atoms are moving at a higher He( g) Ne(g) 2. The lattice energy of a salt is related to the energy required to separate the ions. For which of the following pairs of ions is the energy that is required to separate the i ons largest? (Assume that the distance between the ions in each pair is equal to the sum of the ionic radii. ) Na +(g ) and Cl −(g ) Cs +(g ) and Br −(g ) Mg 2+(g ) and O 2−(g ) Ca 2+(g ) and O 2−(g ) CHEMISTRY Section I 50 Questions Time —90 minutes CALCULATORS ARE NOT ALLOWED FOR SECTION I. Note: For all questions, assume that the temperature is 298 K, the pressure is 1.0 atm, 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 one that is best in each case and then fill in the corresponding circle on the answer sheet. 1. A 0.5 mol sample of He( g) of Ne( g) are placed separately in two 10.0 L rigid containers at 25°C. Each container has a pinhole opening. Which of the gases, , will escape faster thr ough the pinhole and why? (A) He(g ) will escape faster because the (A) average speed than the Ne(g) atoms. (B) (B) Ne(g ) will escape faster because its initial (C) pressure in the container is higher. (D) (C) Ne(g) will escape faster because the atoms have a higher average kinetic energy than the He( g) atoms. (D) Both gases will escape at the same rate because the atoms of both gases have the same average kinetic energy. Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -5-
3. The mass spectrum of element X is presented in the diagram above. Based on the spectrum, which of the following can be concluded about element X? (A) X is a transition metal, and each peak represents an oxidation state of the metal. (B) X contains five electron sublevels. (C) The atomic mass of X is 90. (D) The atomic mass of X is between 90 and 92. 4. Which of the following diagrams best depicts an alloy of Ni and B ? (A) (B) (C) (D) Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -6-
6. A hot iron ball is dropped into a 5. Which of the following is the strongest type of interaction that occurs between the atoms within the circled areas of the two molecules represente above? d (A) Polar covalent bond (B) Nonpolar covalent bond (C) Hydrogen bond (D) London dispersion forces 200. g sample of water initially at 50.° C. If 8.4 kJ of heat is transferred from the ball to the water, what is the final temperature of the water? (The spec ific heat of water is 4.2 J/(g·°C).) (A) 40.°C (B) 51°C (C) 60.°C (D) 70.°C Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -7-
NaHCO ( ) Æ s + HCO ( ) s Na( ) s 3 3 Questions 7-9 refer to the following information. At 27°C , five identical rigid 2.0 L vessels are filled with N2( g ) and sealed. Four of the five vessels also contain a 0.050 mol sample of NaHCO ( ), NaBr( ), Cu( ), or I ( ) s s s s 3 2 , as shown in the diagram above. The volume taken up by the solids is negligible, and the initial pressure of N2( g ) in each vessel is 720 mm Hg. All four vessels are heated to 127°C and allowed to r each a constant pressure. 7. At 127°C, the pressure in vessel 1 is found to be highe r than that in vessel 2. Which of the following reactions best accounts for the observation? (A) (B) NaHCO ( ) Æ s + CO ( ) s NaH( ) s 3 3 Na CO ( ) g + H O( ) 2 NaHCO ( ) s Æ s + CO ( ) g 3 2 3 2 2 (C) N ( ) s + C H ( ) 2 NaHCO ( ) s + g Æ 2 NaNO ( ) g 3 2 3 2 2 (D) Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -8-
8. At 127°C , the entire sample of I2 is observed to have vaporized. How does the mass of vessel 5 at 127°C compare to its mass at 27°C? (A) The mass is less, since the I2 is in the vapor phase. (B) The mass is the same, since the number of each type of atom in the vessel is constant. (C) The mass is greater, since the I2 will react with N2 to form NI 3 , which has a greater molar mass. (D) The mass is greater, since the pressure is greater and the particles have a higher average kinetic energy. 9. The gas particles in vessel 3 at 27°C are represented in the diagram above. The lengths of the arrows represent the speeds of the particles. Which of the following diagrams best represents the particles when vessel 3 is heated to 127°C? (A) (B) (C) (D) Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -9-
10. An acetate buffer solution is prepared by combining 50. mL of 0.20 M acetic acid, HC 2H3O2( aq ), and 50. mL of 0.20 M sodium acetate, NaC 2H3O2( aq). A 5.0 mL sample of 0.10 M NaOH(aq) is added to the buffer solution. Which of the following is a correct pairing of the acetate species present in greater concentration and of the pH of the solution after the NaOH(aq) is added? (The pK aof acetic acid is 4.7.) Acetate Species pH (A) HC 2H3O2 < 4.7 (B) HC 2H3O2 > 4.7 (C) C 2H3O2 - < 4.7 (D) C 2H3O2 - > 4.7 Name Molecular Formula Molar Mass (g/mol) Ethane C 2H6 30 Butane C 4H10 58 11. The molecular formula and molar mass of two straight-chain hydrocarbons are listed in the table above. Based on the information in the table, which compound has the higher boiling point, and why is that compound’ s boiling point higher? (A) C 4H10, because it has more hydrogen atoms, resulting in more hydrogen bonding (B) C 4H10, because it has more electrons, resulting in greater polarizability and stronger dispersion forces (C) C 2H6, because its molecules are smaller and they can get closer to one another, resulting in stronger dispersion forces (D) C 2H6, because its molecules are more polar, resulting in stronger dipole-dipole attractions 12. The first five ionization energies of a second-period element are listed in the table above. Which of the following correctly identifies the element and best explains the data in the table? (A) B, because it has five core electrons (B) B, because it has three valence electrons (C) N, because it has five valence electrons (D) N, because it has three electrons in the p sublevel Mg(OH) 2( s ) Æ Mg 2+(aq) + 2 OH -(aq) ¨ 13. The exothermic dissolution of Mg(OH) 2( s) in water is represented by the equation above. The Ionization Energy (kJ/mol) First 801 Second 2,430 Third 3,660 Fourth 25,000 Fifth 32,820 Kof Mg(OH) 2 is 1.8 ¥ 10 - 11 sp . Which of the following changes will increase the solubility of Mg(OH) 2 in an aqueous solution? (A) Decreasing the pH (B) Increasing the pH (C) Adding NH 3 to the solution (D) Adding Mg(NO 3)2 to the solution Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -10-
− H+ + H 2PO 4 Æ ¨ H3PO 4 Æ ¨ − H + + HPO 4 2 − H2PO 4 = 6.3 × 10−8 Ka2 Æ ¨ 2 − H+ + PO 4 3 − HPO 4 = 4.5 × 10 −13 Ka3 50 mL of 1 M NaH 2PO 4 50 mL of 1 M Na 2HPO 4 Na+ 2 − HPO 4 − H2PO 4 3 − PO 4 14. The heating curve for a sample of pure ethanol is provided above. The temperature was recorded as a 50.0 g sample of solid ethanol was heated at a constant rate. Which of the following explains why the slope of segment T is greater than the slope of segment R ? (A) The specific heat capacity of the gaseous ethanol is less than the specific heat capacity of liquid ethanol. (B) The specific heat capacity of the gaseous ethanol is greater than the specific he at capacity of liquid ethanol. (C) The heat of vaporization of ethanol is less than the heat of fusion of ethanol. (D) The heat of vaporization of ethanol is greater than the heat of fusion of ethanol. K = 7.2 × 10 −3 a1 15. A solution is prepared by mixing with . On the basis of the information above, which of the following species is present in the solution at the lowest concentration? (A) (B) (C) (D) Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -11-
2 XY(g) Æ X 2(g ) + Y 2(g ) ¨ K = 230p 16. A certain gas, XY(g ), decomposes as represented by the equation above. A sample of each of the three gases is put in a previously evacuated container. The initial partial pressures of the gases are shown in the table below. Gas Initial Partial Pressure (atm) XY 0.010 X 2 0.20 Y 2 2.0 The temperature of the reaction mixture is held constant. In which direction will the reaction proceed? (A) The reaction will form more products. (B) The reaction will form more reactant. (C) The mixture is at equilibrium, so there will be no change. (D) It cannot be determined unless the volume of the container is known. Questions 17-20 refer to the following information. A 0.35 g sample of Li(s) is placed in an Erlenmeyer flask containing 100 mL of water at 25°C. A balloon is placed over the mouth of the flask to collect the hydrogen gas that is generated. After all of the Li( s) has reacted with H2O(l ), the solution in the flask is added to a clean, dry buret and used to titrate an aqueous solution of a monoprotic acid. The pH curve for this titration is shown in the diagram below. 17. Which of the following changes will most likely increase the rate of reaction between Li(s) and water? (A) Using 125 mL of water instead of 100 mL (B) Using a 0.25 g sample of Li( s) instead of a 0.35 g sample (C) Using a 0.35 g sample of Li( s) cut into small pieces (D) Decreasing the water temperature before adding the Li( s) 18. What will be the effect on the amount of gas produced if the experiment is repeated using 0.35 g of K(s) instead of 0.35 g of Li(s) ? (A) No gas will be produced when K(s) is used. (B) Some gas will be produced but less than the amount of gas produced with Li(s). (C) Equal quantities of gas will be produced with the two metals . (D) More gas will be produced with K(s) than with Li( s). Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -12-
pK a 19. On the basis of the pH curve, the value of the acid is closest to (A) 4 (B) 5 (C) 8 (D) 12 20. Which of the following is t he balanced net-ionic equation for the reaction between Li(s) and water? (A) 2 Li(s) + 2 H +(aq) + 2 OH −(aq) → 2 Li +(aq) + 2 OH −(aq) + H 2(g ) (B) 2 Li( s) + 2 H 2O(l) → 2 Li +(aq) + 2 OH −(aq) + H 2(g ) (C) 2 Li( s) + 2 H 2O(l) → 2 LiOH( s) + H 2(g ) (D) 2 Li( s) + 2 H 2O(l) → 2 LiH( s) + H 2(g ) Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -13-
21. Benzene,C 6H6, has the structure shown above. Considering the observation that benzene is only sparingly soluble in water, which of the following best describes the intermolecular forces of attraction between water and benzene? (A) Benzene is nonpolar, therefore there are no forces between water and benzene. (B) The H atoms in benzene form hydrogen bonds with the O atoms in water. (C) Benzene is hydrophobic, therefore there is a net repulsion between water and benzene. (D) There are dipole-induced dipole and London dispersion interactions between water and benzene. Solution Acid K a 1 CH 3CO 2H 1.75 ¥ 10 - 5 2 CF 3CO 2H 1.0 ¥ 10 0 22. Acid-dissociation constants of two acids are listed in the table above. A 20. mL sample of a 0.10 M solution of each acid is titrated to the equivalence point with 20. mL of 0.10 M NaOH. Which of the following is a true statement about the pH of the solutions at the equivalence point? (A) Solution 1 has a higher pH at the equivalence point because CH 3CO 2His the stronger acid. (B) Solution 1 has a higher pH at the equivalence point because CH 3CO 2H has the stronger conjugate base. (C) Solution 1 has a lower pH at the equivalence point because CH 3CO 2H is the stronger acid. (D) Solution 1 has a lower pH at the equivalence point because CH 3CO 2H has the stronger conjugate base. 23. A 1.0 g sample of a cashew was burned in a calorimeter containing 1000. g of water, and the temperature of the water changed from 20.0°C to 25.0°C. In another experiment, a 3.0 g sample of a marshmallow was burned in a calorimeter containing 2000. g of water, and the temperature of the water changed from 25.0°C to 30.0°C. Based on the data, which of the following can be concluded about the energy content for 1.0 g of each of the two substances? (The specific heat of water is 4.2 J/(g ⋅°C).) (A) The combustion of 1.0 g of cashew releases less energy than the combustion of 1.0 g of marshmallow. (B) The combustion of 1.0 g of cashew releases the same amount of energy as the combustion of 1.0 g of marshmallow. (C) The combustion of 1.0 g of cashew releases more energy than the combustion of 1.0 g of marshmallow. (D) No comparison can be made because the two systems started with different masses of food, different masses of water, and different initial temperatures. Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -14-
NO( g) and O2(g ) 24. The reaction between to produce NO 2( g ) in a rigid reaction vessel is represented in the diagram above. The pressure inside the container is r ecorded using a pressure gauge. Which of the following statements correctly predicts the change in pressure as the reaction goes to completion at constant temperature, and provides the correct explanation? (A) The pressure will increase because the product molecules have a greater mass than either of the reactant molecules. (B) The pressure will decrease because there are fewer molecules of product than of reactants. (C) The pressure will decrease becau se the product molecules have a lower average speed than the reactant molecules. (D) The pressure will not change because the total mass of the product molecules is the same as the total mass of the reactant molecules. Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -15-
Questions 25-29 refer to the following information. 2 H 2O2(aq) Æ 2 H 2O(l ) + O 2(g ) D H ° = −196 kJ/mol rxn The decomposition of H2O2(aq) is represented by the equation above. A student monitored the decomposition of a 1.0 L sample of H2O2( aq) at a constant temperature of 300. K and recorded the concentration of H2O2as a function of time. The results are given in the table below. Time (s)[H 2O2] 0 2.7 200. 2.1 400. 1.7 600. 1.4 25. Which of the following identifies the element(s) being oxidized and reduced in the reaction? (A) Hydrogen is oxidized and oxygen is reduced. (B) Oxygen is oxidized and hydrogen is reduced. (C) Oxygen is both oxidized and reduced. (D) No elements are oxidized or reduced; the reaction is not a redox reaction. 26. The O2( g ) produced from the decomposition of the 1.0 L sample of H2O2(aq) is collected in a previously evacuated 10.0 L flask at 300. K . What is the approximate pressure in the flask after 400. s ? (For estimation purposes, assume that 1.0 mole of gas in 1.0 L exerts a pressure of 24 atm at 300. K.) (A) 1.2 atm (B) 2.4 atm (C) 12 atm (D) 24 atm 27. Which of the following statements is a correct interpretation of the data regarding how the order of the reaction can be determined? (A) The reaction must be first order because there is only one reactant species. (B) The reaction is first order if the plot of ln [H 2O2] versus time is a straight line. (C) The reaction is first order if the plot of 1/[H 2O2] versus time is a straight line. (D) The reaction is second order because 2 is the coefficient of H2O2 in the chemical equation. 28. The reaction is thermodynamically favorable. The signs of Δ G ° and ΔS° for the reaction are which of the following? Δ G ° ΔS° (A) Positive Positive (B) Negative Positive (C) Positive Negative (D) Negative Negative Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -16-
29. Assume that the bond enthalpies of the oxygen- hydrogen bonds in H2O are not significantly different from those in H2O2. Based on the value of Δ H ° of the reaction, which of the following could be the bond enthalpies (in kJ/mol) for the bonds broken and formed in the reaction? O–O in H 2O2 O =O in O 2 O–H (A) 300 500500 (B) 150 500500 (C) 500 300150 (D) 250 300150 30. Which of the following accounts for the observation that the pH of pure water at 37°C is 6.8 ? (A) At 37∞C water is naturally acidic. (B) At 37∞C the autoionization constant for water, Kw, is larger than it is at 25 ∞C. (C) At 37∞C water has a lower density than it does at 25∞C; therefore, [H +] is greater. (D) At 37∞C water ionizes to a lesser extent than it does at 25 ∞C. 31. To gravimetrically analyze the silver content of a piece of jewelry made from an alloy of Ag and Cu, a student dissolves a small preweighed sample in HNO 3( aq). Ag +(aq) and Cu 2+(aq) ions form in the solution. Which of the following should be the next step in the analytical process? (A) Centrifuging the solution to isolate the heavier ions (B) Evaporating the solution to recover the dissolved nitrates (C) Adding enough base solution to bring the pH up to 7.0 (D) Adding a solution containing an anion that forms an insoluble salt with only one of the metal ions 32. A sample of a compound that contains only the elements C, H, and N is completely burned in O2to produce , , and some NO 2. A possible empirical formula of the compound is (A) CH 2N (B) CH 5N (C) C 2H5N (D) C 3H3N2 HF(aq) + H 2O(l) Æ H 3O+(aq) + F −(aq) ¨ 33. The dissociation of the weak acid 44.0 g of CO 2 45.0 g of H 2O HFin water is represented by the equation above. Adding a 1.0 mL sample of which of the following would increase the percent ionization of HF( aq) in 10 mL of a solution of 1.0 M HF ? (A) 1.0 M KF (B) 1.0 M H 2SO 4 (C) 10.0 M HF (D) Distilled water Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -17-
CaC ( ) s (molar mass 64 g/mol) 2 Ca(OH) 2 100. mL of NaOCl(aq) NaOCl(aq) 2 sp to sp Questions 34-36 refer to the reactions represented below, which are involved in a demonstration commonly known as “underwater fireworks.” Reaction 1: CaC 2(s) + 2 H 2O( l) C 2H2(g) + Ca(OH) 2(s ) Reaction 2: NaOCl( aq) + 2 HCl(aq ) Cl 2(g) + NaCl( aq) + H 2O(l) Reaction 3: C2H2(g) + Cl 2(g) C 2H2Cl 2(g) 34. Ca(OH) ( ) s 2 precipitates when a 1.0 g sample of 36. When Reaction 3 occurs, does the hybridization of the carbon atoms change? CaC ( ) s 2 is added to 1.0 L of distilled water at room temperature. If a 0.064 g sample of (A) Yes; it changes from . is used instead 3 sp to sp (B) Yes; it changes from . and all of it reacts, which of the following will (C) Yes; it changes from sp 2 to sp 3. occur and why? (The value of K sp for (D) No; it does not change. is 8.0 10 8.) (A) Ca(OH) 2 will precipitate because Q > K sp. (B) Ca(OH) 2 will precipitate because Q < K sp. (C) Ca(OH) 2 will not precipitate because Q > K sp . (D) Ca(OH) 2 will not precipitate because Q < K sp . 35. Reaction 2 occurs when an excess of 6 M HCl( aq) solution is added to of unknown concentration. If the reaction goes to completion and 0.010 mol of Cl 2(g ) is produced, then what was the molarity of the solution? (A) 0.0010 M (B) 0.010 M (C) 0.10 M (D) 1.0 M Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -18-
Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -19- Ka HC 3H5O3( aq ) 8.3 × 10 − 4 CH 3NH 3 +( aq) 2.3 × 10 −11 37. The acid-dissociation constants of HC 3H5O3(aq) and CH 3NH 3+( aq) are given in the table above. Which of the following mixtures is a buffer with a pH of approximately 3 ? (A) A mixture of 100. mL of 0.1 M CH 3NH 3Cl and 50. mL of 0.1 M NaOH (B) A mixture of 100. mL of 0.1 M HC 3H5O3 and 50. mL of 0.1 M NaOH (C) A mixture of 100. mL of 0.1 M NaC 3H5O3 and 100. mL of 0.1 M NaOH (D) A mixture of 100. mL of 0.1 M CH 3NH 3Cl and 100. mL of 0.1 M CH 3NH 2 38. The Lewis electron-dot diagrams of the HClO3 molecule and the HClO 2molecule are shown above at the left and right, respectively. Which of the following statements identifies the stronger acid and correctly identifies a factor that contributes to its being the stronger acid? (A) HClO 3(aq) is the stronger acid because its molecules experience stronger London dispersion forces. (B) HClO 3(aq) is the stronger acid because the additional electronegative oxygen atom on the chlorine atom stabilizes the conjugate base. (C) HClO 2(aq) molecules experience weaker London dispersion forces. is the stronger acid because its (D) HClO 2(aq) is the stronger acid because the 39. If equal masses of the following compounds undergo complete combustion, which will yield the greatest mass of CO 2? (A) Benzene, C6H6 (B) Cyclohexane, C6H12 (C) Glucose, C 6H12O6 (D) Methane, CH 4 CaCO 3( s) Æ ¨ CaO( s) + CO 2(g ) D H ° = 178 kJ/mol rxn 40. The reaction system represented above is at equilibrium. Which of the following will decrease the amount of CaO(s) in the system? (A) Increasing the volume of the reaction vessel at constant temperature (B) Lowering the temperature of the system (C) Removing some CO 2( g ) at constant temperature (D) Removing some CaCO 3( s) at constant temperature Acid Solution Volume of NaOH Added (mL) A 40 B 75 C 115 D 200 lone pairs of electrons on the chlorine atom stabilize the conjugate base. 41. To maximize the yield in a certain manufacturing process, a solution of a weak monoprotic acid that has a concentration between 0.20 M and 0.30 M is required. Four 100. mL samples of the acid at different concentrations are each titrated with a NaOH 0.20 M solution. The volume of NaOH needed to reach the end point for each sample is given in the table above. Which solution is the most suitable to maximize the yield? (A) Solution A (B) Solution B (C) Solution C (D) Solution D
Cl(g ) + O 3(g ) → ClO( g) + O 2(g ) slow step ClO(g ) + O 3(g ) → Cl( g) + 2 O 2(g ) fast step 2 O 3( g ) → 3 O 2(g ) overall reaction Δ H = −285 kJ/mol rxn Rate = k[O 3]2 Rate = k[ClO] [O 3]2 ㌁ 孏 ] 2 剡瑥‽ k 2 [O ] 3 Questions 42-44 refer to the following information. When free Cl(g ) atoms encounter O3(g ) molecules in the upper atmosphere, the following reaction mechanism is proposed to occur. 42. Which of the following rate laws for the overall reaction corresponds to the proposed mechanism? (A) (B) Rate = k[Cl] [O 3] (C) (D) Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -20-
X + O 3 → XO + O 2 XO + O 3 → X + 2 O 2 2 O → 3 O 43. Which of the following reaction energy profiles best corresponds to the proposed mechanism? (A) (B) (C) (D) 3 2 44. The proposed mechanism can be written in a more general form, as shown above. Species other than Cl can also decompose O3 through the same mechanism. Which of the following chemical species is most likely to decompose O3 in the upper atmosphere through the above mechanism? (A) He (B) Br (C) N2 (D) O2 Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -21-
is added to a solution 1 孒崠㴠 孑] ㈁= 孑崠㴠 存] 2 = = = = 䡘(aq) + Y −( aq) Æ ¨ HY( aq) + X −(aq) K > 1 eq 45. A solution of a salt of a weak acid HY of another weak acid HX . Based on the information given above, which of the following species is the strongest base? (A) HX(aq) (B) Y−( aq) (C) HY(aq) (D) X−(aq) X( g) + 2 Q(g ) Æ ¨ R( g) + Z(g ) Kc = 1.3 × 10 5 at 50°C 46. A 1.0 mol sample of X(g) and a 1.0 mol sample of Q(g) are introduced into an evacuated, rigid 10.0 L container and allowed to reach equilibrium at 50°C according to the equation above. At equilibrium, which of the following is true about the concentrations of the gases? (A) (B) (C) [R] = [Z] > [Q] (D) [X] = [Q] = [R] = [Z] Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -22-
47. The potential energy of a system of two atoms as a function of their internuclear distance is shown in the diagram above. Which of the following is true regarding the forces between the atoms when their internuclear distance is x ? (A) The attractive and repulsive forces are balanced, so the atoms will maintain an average internuclear distance x. (B) There is a net repulsive force pushing the atoms apart, so the atoms will move further apart. (C) There is a net attractive force pulling the atoms together, so the atoms will move closer together. (D) It cannot be determined whether the forces between atoms are balanced, attractive, or repulsive, because the diagram shows only the potential energy. Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -23-
X(g) + 2 Y( g) Æ XY 2(g ) 48. In order to determine the or der of the reaction represented above, the initial rate of formation of XY 2 is measured using different initial values of [X] and [Y] . The results of the experiment are shown in the table below. Trial [X][Y] Initial Rate of Formation of XY 2 (M s -1) 1 0.50 0.50 8.0 ¥ 10 - 3 2 1.00 0.50 3.2 ¥ 10 - 2 3 1.00 1.00 6.4 ¥ 10 - 2 In trial 2 which of the reactants would be consumed more rapidly, and why? (A) X, because it has a higher molar concentration. (B) X, because the reaction is second order with respect to X. (C) Y, because the reaction is second order with respect to Y. (D) Y, because the rate of disappearance will be double that of X. 49. In a paper chromatography experiment, a sample of a pigment is separated into two components, X and Y, as shown in the figure above. The surface of the paper is moderately polar. What can be concluded about X and Y based on the experimental results? (A) X has a larger molar mass than Y does. (B) Y has a larger molar mass than X does. (C) X is more polar than Y. (D) Y is more polar than X. Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -24-
50. The diagram above represents the absorption spectrum for a pure molecular substance. Which of the following correctly indicates the type of transition observed for the substance in each of the regions of the absorption spectrum? Region X Region Y Region Z (A) Molecular vibration Molecular rotation Electronic transition (B) Electronic transition Molecular rotation Molecular vibration (C) Molecular rotation Molecular vibrationElectronic transition (D) Electronic transition Molecular vibrationMolecular rotation Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -25-
________________________________ END OF SECTION I IF YOU FINISH BEFORE TIME IS CALLED, YOU MAY CHEC K 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 SHEET WRITTEN AND GRIDDED YOUR AP NUMBER CORRECTLY ON YOUR ANSWER SHEET TAKEN THE AP EXAM LABEL FROM T HE FRONT OF THIS BOOKLET AND PLACED IT ON YOUR ANSWER SHEET • • • Unauthorized copying or reuse of any part of this page is illegal. -2 6-
Section I I: Free- Response Questions This is the free-response section of the 201 5 AP exam. It includes cover material and other administrative instructions to help familiarize students with the mechanics of the exam. (Note that future exams may differ in look from the following content.)
AP ® Chemistry Exam SECTION II: Free Response 2015 DO NOT OPEN THIS BOOKLET UNTIL YOU ARE TOLD TO DO SO. At a Glance Total Time 1 hour, 45 minutes Number of Questions 7 Percent of Total Score 50% Writing Instrument Either pencil or pen with black or dark blue ink Electronic Device Calculator allowed Suggested Time Approximately 23 minutes each for questions 1 3 and 9 minutes each for questions 4 7 Weight Approximate weights: Questions 1 3: 22% each Questions 4 7: 9% each Instructions The questions for Section II 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 organize your answers or for scratch work, but you must write your answers in the areas designated for each response. Only material written in the space provided will be scored . Examples and equations may be included in your responses where appropriate. For calculations, clearly show the method used and the steps involved in arriving at your answers. You must show your work to receive credit for your answer. Pay attention to significant figures. Write clearly and legibly. Cross out any errors you make; erased or crossed- out work will not be scored. Manage your time carefully. You may proceed freely from one question to the next. You may review your responses if you finish before the end of the exam is announced . Form I Form Code 4LBP4-S 25
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L, mL = liter(s), milliliter(s) mm Hg = millimeters of mercury g = gram(s) E = h c = = frequency Planck’s constant, h = 6.626 10 34 Js Speed of light, c = 2.998 10 8 ms 1 Avogadro’s number = 6.022 10 23 mol 1 Electron charge, e = 1.602 × 10 19 coulomb K c = [C] [D] [A] [B] c d a b , where a A + b B c C + d D K p = C D A B () ( ) () ( ) c d a b P P P P K a = [H ][A ] [HA] + - K b = [OH ][HB ] [B] - + K w = [H +][OH ] = 1.0 10 14 at 25 C = K a K b 灈‽⁰ K a + log [A ] [HA] - Kc (molar concentrations) K w (water) ln[A]t ln[A] 0 = kt [] [] 0 A A 1 1 t - = kt t ½ = 0.693 k t ½ = half-life AP ® CHEMISTRY EQUATION S AND CONSTANTS Throughout the exam the following symbols have th e definitions specified unless otherwise noted. J, kJ = joule(s), kilojoule(s) nm = nanometer(s) V = volt(s) atm = atmosphere(s) mol = mole(s) ATOMIC STRUCTURE E = energy = wavelength EQUILIBRIUM pH = log [H +] , pOH = log [OH ] 14 = pH + pOH p K a = log K a , pK b = log K b Equilibrium Constants K p (gas pressures) K a (weak acid) K b (weak base) KINETICS k = rate constant t = time -3-
1 atm = 760 mm Hg = 760 torr PV = nRT 浯汥猠䄠 PA = P total X A, where X A = total moles = P A + P B + P C + . . . P total m n = M K = C + 273 D = m V 1 2 KE per molecule = mv 2 A = abc M = molar mass KE = kinetic energy A = absorbance R = 8.314 J mol 1K1 = 62.36 L torr mol 1K1 S = Â S products - Â S reactants H = Â D H f products - Â DH f reactants G = Â D G f products - Â DG reactants f G = H T S = RT ln K = nF E q I = t S = standard entropy H = standard enthalpy G = standard Gibbs free energy E = standard reduction potential F = 96,485 coulombs per mole of electrons Faraday’s constant, ㄠ橯畬e ㄠ癯汴 㴠 ㄠ捯畬潭戠 GASES, LIQUIDS, AND SOLUTIONS Molarity, M = moles of so lute per liter of solution THERMODYNAMICS / ELECTROCHEMISTRY q = mcT P = pressure V = volume T = temper ature n = number of moles m = mass D = density v = velocity a = molar absorptivity b = path length c = concentration Gas constant, = 0.08206 L atm mol 1K1 STP = 273.15 K and 1.0 atm Ideal gas at STP = 22.4 L mol −1 q = heat m = mass c = specific heat capacity T = temper ature n = number of moles I = current (amperes) q = charge (coulombs) t = time (seconds) -4-
SECTION II BEGINS ON PAGE 6. -5-
CHEMISTRY CHEMISTRY Section II 7 Questions Time—1 hour and 45 minutes YOU MAY USE YOUR CALCULATOR FOR THIS SECTION. Directions: Questions 1–3 are long free-response questions that require about 23 minutes each to answer and are worth 10 points each. Questions 4–7 are short free-response que stions that require about 9 minutes each to answer and are worth 4 points each. Write your response in the space provided following each question. Examples and equa tions may be included in your responses where appropriate. For calculations, clearly show the method used and the steps involved in arriving at your answers. You must show your work to receive credit for your answer. Pay attention to significant figures. Half-Reaction E° (V) 2 CO 2( g ) + 12 H +(aq) + 12 e − Æ C 2H5OH(aq) + 3 H 2O(l) − 0.085 O 2( g ) + 4 H +(aq) + 4 e − Æ 2 H 2O(l) 1.229 1. A student uses a galvanic cell to determine the concentration of ethanol, C 2H5OH, in an aqueous solution. The cell is based on the half-cell reactions represented in the table above. (a) Write a balanced equation for the ove rall reaction that occurs in the cell. (b) Calculate E ° for the overall reaction that occurs in the cell. (c) A 10.0 mL sample of C2H5OH(aq) is put into the electrochemical cell. The cell produces an average current of 0.10 amp for 20. seconds, at which point the C2H5OH(aq) has been totally consumed. (i) Calculate the charge, in coulombs, that passed through the cell. (ii) Calculate the initial [C 2H5OH] in the solution. An alternative approach to determine the concentration of C2H5OH(aq) in a solution is based on the reaction represented below. 3 C 2H5OH(aq) + 2 Cr 2O7 2 − (aq) + 16 H +(aq) Æ 4 Cr 3+(aq) + 3 CH 3COOH(aq) + 11 H 2O( l) orange blue-green Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -6-
A solution has an initial Cr 2O72 − (aq) concentration of 1.0 × 10 − 3 M and an initial C2H5OH(aq ) concentration of 0.500 M. The solution contains enough strong acid to keep the pH essentially constant throughout the reaction. The student places a sample of the solution in a cuvette that has a path length of 0.50 cm and places it in a spectrophotometer set to measure absorbance at 440 nm. (Cr 2O72 − (aq) is the only species in the reaction mixture that absorbs light at th is wavelength.) The absorbance of Cr 2O72 − (aq) in the solution is monitored as the reaction proceeds; the table below shows the abso rbance as a function of time for the first trial. Time (min) Absorbance at 440 nm 0.00 0.782 1.50 0.553 3.00 0.389 4.50 0.278 6.00 0.194 (d) Calculate the value of [Cr 2O7 2 − ] at 1.50 min. (e) The student runs a second trial but this time uses a cuvette that has a path length of 1.00 cm. Describe how the experimental setup should be ad justed to keep the initial absorbance at 0.782 . Justify your answer with respect to the factors that influence the absorbance of a sample in a spectrophotometer. For the concentrations of reactants used in the experiment, the rate of the reaction can be written as follows. Rate = k observed [Cr 2O72 − ]y, where k observed = k[C 2H5OH] (f) Explain how the experimental data indicate th at the reaction is first order with respect to 2 −Cr 2O7 . Unauthorized copying or reuse of any part of this page is illegal. GO ON TO THE NEXT PAGE. -7-
ADDITIONAL PAGE FOR ANSWERING QUESTION 1 GO ON TO THE NEXT PAGE. -8-
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