You must sign to affirm that you have followed the UNC Charlotte Student Code of Academic Integrity, or your exam will not be graded.
You may assume the 5% rule on all problems without checking the rule. Please read each question carefully and answer it completely and clearly. Most of the factual information you need is contained in the text of the problem. Answer the questions you find easy first; questions which appear difficult at first usually require a revision of your thought process. Always keep in mind the intended examination topics if a problem appears too hard. The quiz should have 5 pages for a total of 10 questions. Individual point values for free response are given in the corner of each answer space. You must show your work to receive any credit for problems involving calculations. All calculated answers and work must include units, and should be rounded to the appropriate number of significant figures!
88.91
1
A
Free Response Instructions: Solve the following problems in the boxes provided below each question.
Be sure to show all your work and units, and round your answers to the appropriate significant figures at the end of each part. FOR ALL PARTS: 1 for MISSING UNITS 1. A 100.0 mL sample of 0.100 M methylamine (CH3NH2, Kb = 3.710‐4) is titrated with 0.250 M HNO3. (a) Calculate the pH after the addition of 15.0 mL of acid. CH3NH2(aq) + H3O+(aq) CH3NH3+(aq) + H2O(l) +1 correct reaction 0.0100 mol 0.00375 mol 0 mol |
+1 correct BCA B
C
‐0.00375 mol ‐0.00375 mol + 0.00375 mol |
+1 Kb Ka ‐14
‐4
0.00625 mol 0 mol 0.00375 mol Ka = 1.010 /3.710 = 2.710‐11 A
+1 H‐H equation setup with base/acid (consistent)
+1 answer ‐14 / 3.710‐4) + log (0.00625 mol / 0.00375 mol) = 10.79 pH = log(1.010 5 (b) What is the pH at the equivalence point? 0.1000 L(0.100 M CH3NH2) = 0.0100 mol CH3NH2 0.0100 mol H3O+ = 0.250 M HNO3(V) V = 0.0400 L For incorrect reactions, +3 maximum.
CH3NH2(aq) + H3O+(aq) CH3NH3+(aq) + H2O(l) 0.0100 mol 0.0100 mol 0 mol | +1 correct reaction + After B
C
‐0.0100 mol ‐0.0100 mol + 0.0100 mol | +1 Vtot, +1 mol M (consistent) +
NH
A
0 mol 0 mol 0.0100 mol |
[CH
3
3 ] = 0.0100 mol / 0.140 L
= 0.071429 M CH3NH3+ +1 correct reaction/ICE table +
+
+1 Ka setup with correct Ka CH
3NH3 (aq) + H2O(l) CH3NH2(aq) + H3O (aq) ‐11 = x2 / 0.071429 M ‐ x 0 M 0 M 2.70310
I
0.071429 M | ‐x | + x
+x
x = 1.38910‐6 +1 answer C x x pH = ‐log(x) = 5.86
0.071429 M – x | E
6
(c) What major post‐equivalence point species are present? (List species present AFTER the strong reaction but BEFORE equilibrium is established.)
H2O
H3O+
CH3NH3+
+1/2 each
NO3
2
(d) In part (c), what effect allows you to ignore the weak acid in solution when calculating the pH? Explain. If “weak versus strong,” +1 description. Common‐ion effect: +1 Although CH3NH3+ is present, H3O+ is a common‐ion (product) in the reaction +2 common‐ion explained CH3NH3+(aq) + H2O(l) CH3NH2(aq) + H3O+(aq), so this reaction will be suppressed.
3
2. (a) Describe how to make 1.00 L of 1:1 HCO3/CO32 buffer solution from solid Na2CO3 and 1.00 M HCl.
(Assume that the solid does not displace the volume of the solution.) Be specific with numerical amounts! +4 ratio of 2 (weak base): 1(strong
Exam 1 Review Notes Overview-- 50 questions, Multiple Choice. Similar format to practice exam. Need to bring a #2 pencil. Scantrons will be provided. The goal is to have no trick questions. Answers will be straightforward and will not be convoluted. Normally, you can eliminate 3 of the 5 answers … if you are still confused go back to the question for a possible indication of what the correct answer is. Usually there will be a key word or phrase that will clue you in to the correct answer…
Office: 316 Prentis Hall Telephone: (313) 577-4581 (Office) (313) 577-4515 (Dept. of Management) Fax: (313) 577-5486 E-Mail: a.levi@wayne.edu or alevi@sbcglobal.net Office hours: Thursdays 2:00 - 4:00 PM or by appointment Course Prerequisite BA 7040 (Managing Organizational Behavior) Course description The importance of human resource management (HRM)—the use of a firm’s human resources to achieve organizational objectives—has increased steadily…
relevant sections from the text book, including key definitions and examiners' tips. Answer questions from the text book at the end of each double page. Have a go at practice questions and examination questions at the end of each chapter. Check through the specification (found at www.ocr.org.uk) to make sure you understand the concepts you have covered in class. Learn your definitions for key words. Practice calculations for magnification. Work through past exam papers and look at mark schemes to see what…
Rationale and context for the project (750 words) In my current role as head of Physics the performance of pupils in terminal exams at Key Stage 5 is of significant concern. My year 12 pupils progressed well throughout the course between September 2012 and June 2013. This was demonstrated throughout various assessments during the year. When they reached their terminal exams however the entire cohort performed significantly lower than the ability demonstrated to me through my own assessment. This year…
Decision Making (SOU) Semester 5, 2012 Examination Information for ORDINARY, DEFERRED AND SUPPLEMENTARY EXAMINATIONS Time Allowed: THREE (3) hours + 15 minutes reading time (you are permitted to write during reading time) Instructions: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. There are SIX (6) questions to be marked out of a total 100 marks. Some questions have more than one part. Answer ALL questions. You may answer the questions in any order but PLEASE clearly identify…
HaisLee Gillette January 13, 2015 EMS OREGON RULES AND REGULATIONS 333.265 Assignment 1. Define scope of practice- "Scope of Practice" means the maximum level of emergency or non-emergency care that an EMS provider may provide that is set forth by the rules adopted by the Oregon Medical Board. 2.What free does Oregon charge EMTs for their initial application and same day practical examinations- The initial application and same-day practical examination fees for EMTs: -EMT — $110 3.How many clinical…
also make note of the types of questions that will be on the exam- multiple choice and true/ false. Day 2: Write down key points talked about in class. Review your notes and read chapter 2 to prepare for the next class. 2 Day 3: After class review your notes and then visit your teacher in their office hours to clear up anything that you got caught up with during the week, then create some space for yourself tonight to read chapter 3 Day 4: Ask questions in class about any information about last week…
MGMT 2002 Managing Business Communication Course Outline Semester 2, 2014 Part A: Course-Specific Information Part B: Key Policies, Student Responsibilities and Support Table of Contents PART A: COURSE-SPECIFIC INFORMATION 1 STAFF CONTACT DETAILS Lecturer-in-charge: Ray Durham Room: 5th floor, School of Management, ASB Phone No: 9385 9779 Email: raydurham@unsw.edu.au Consultation Times – Wednesday 9am to 10am (or by appointment)…