{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Fall 01. Exam2 key

Fall 01. Exam2 key - Chem 2101 Hour Exam IV NAME 2001 Chem...

Info icon This preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
Chem 2101 Hour Exam IV 2001 NAME
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Chem 2101 Hour Exam IV 2001 If you do NOT want me to return your exam in the big pile -> check this box A -> and give us your e-mail address: Your Name: This Exam Will be filled out by graders. Score: 1. /45 Previous Exams My score hour exam I 2. /15 My score hour exam II 3. /20 My score hour exam III 4. /20 To the students: Please check your scores after you get the exam back and contact Phil Buhlmann if any of these scores is incorrect. Total: /100 Please note that we do this as a service to you. We try to do our best to detect any errors as early as possible. Instructions: * Use equations and tables provided on exam as needed * Show all work for which you expect credit * Put your name on every page * Write in ink to be eligible for a regrade
Image of page 2
Chemistry 2101 Introductory Analytical Chemistry Fall 2001 This sheet of equations will be provided on the fourth Hour Exam. Note that you are still responsible for knowing what the equations mean, and how to apply them. Ox + n e - == Red, E = E o - 0.059 V n log [Red] [Ox] {at 25 o C}; E = E o - R T n F ln [Red] [Ox] E = E o + R T F n x ln { a X + k x,y a Y n x /n y } E = E o + 0.059 V n x log { a X + k x,y a Y n x /n y } {at 25 o C} Use standard reduction potentials from the attached table wherever needed.
Image of page 3

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Name 1 An electrochemical measurement involving a sample of Cr 2 O 7 2- and Cr 3+ . (a) (5 points) A solution in contact with a platinum working electrode is 10 -3 M in Cr 2 O 7 2- and 10 -2 M in Cr 3+ . Formulate the reduction-oxidation reaction involving the two chromium species at the platinum electrode. Cr 2 O 7 2- + 14 H + + 6 e - == 2 Cr 3+ + 7 H 2 O (b) (10 points) If the pH is 2.0 and the temperature 25 o C, what is the potential of the half cell described in (a)? E = E o - 0.059 V n log [Red] [Ox] = E = 1.36 V - 0.059 V 6 log [Cr 3+ ] 2 [Cr 2 O 7 2- ] [H + ] 14 = E = 1.36 V - 0.059 V 6 log (10 -2 ) 2 (10 -3 ) (10 -2 ) 14 = 1.09 V
Image of page 4
Name (c) (5 points) The above mentioned half cell with the two chromium species is now combined with a silver/silver chloride reference electrode to give an electrochemical cell. Draw a schematic of the resulting electrochemical cell. Assume that the solution in contact with the electrode is saturated with KCl. The bridge electrolyte is 3.5 M KCl.
Image of page 5

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern