Electrochemistry

5 May 2017

SOP4CV - A Web Resource for Cyclic Voltammetry Information

Submitted by Gerard Rowe, University of South Carolina Aiken
Description: 

http://sop4cv.com/

This is a great website created by Dr. Daniel Graham (who has the distinction of publishing a paper featured on TOC ROFL) to give anyone a working understanding of cyclic voltammetry techniques, their physical background, and the interpretation of their results.  

Prerequisites: 
Corequisites: 
Subdiscipline: 
Learning Goals: 

Students will gain experience interpreting the basic features of cyclic voltammograms, including: half-potential, electrochemical reversibility, chemical reversibility, and scan rate dependence

Students will learn the physical origins of the "duck" shape of a reversible CV using the Nernst equation and diffusion concepts

Students will learn what analytical methods are available using CV

Implementation Notes: 

None yet.  I'm considering creating an activity using the information in this website, but for now I just wanted to share this resource.

10 Apr 2017

Redox Chemistry and Modern Battery Technology

Submitted by Zachary Tonzetich, University of Texas at San Antonio
Evaluation Methods: 

I do not grade this activity, but if I did, I would look for class participation in the discussion or assign several of the questions to be turned in at a later date.

Evaluation Results: 

My impression of this activity is that it really helps students see the value of redox chemistry. In my experience, the aspects of redox chemistry we teach students (balancing equations, calculating cell potentials, etc.) seem both difficult and esoteric. This activity reinforces these concepts while demonstrating their importance to modern life. One of the biggest realizations the students come to is the relationship between cell voltage and the mass of the materials involved in the redox reaction.

Description: 

This In-Class Activity is a series of instructor-guided discussion questions that explore lithium-ion batteries through the lens of simple redox chemistry. I use this exercise as a review activity in my Descriptive Inorganic Chemistry course to help prepare for examinations. However, my primary purpose with this exercise is to impress upon students how basic concepts in redox chemistry and solid-state structure are directly relevant to technologies they use everyday. I do not focus too heavily on the design or operation of the batteries themselves, as other exercises published on VIPEr already do a very good job of that. My intention is to demonstrate how a basic knowledge of redox chemistry is the first step in understanding seemingly complex technologies.

Learning Goals: 

The primary goal of this In-Class Activity is for students to solidify their understanding of redox reactions, cell voltages and the relationship between electrical energy and potential. The exercise is also designed to show students how these considerations are part of the design of modern batteries. A secondary aspect of the activity explores the solid-state structure of metal-oxides and how these materials are important to the operation of the battery. At the conclusion of the activity, the student should be familiar enough with calculaing cell voltages and free energy changes that they can critically evaluate the components of a standard battery.

Equipment needs: 

None.

Course Level: 
Prerequisites: 
Corequisites: 
Implementation Notes: 

I display the pdf file on screen and use the white board to work out simple arithmetic aspects of the exercise, while soliciting responses from the class.

Time Required: 
45 minutes
27 Mar 2017

Nanomaterials for Carbon Dioxide Reduction

Submitted by Anne Bentley, Lewis & Clark College
Evaluation Methods: 

The problems presented here represented half the points on the final exam – I have included point totals to give an idea of the weight assigned to each problem.

Evaluation Results: 

Twelve students were enrolled in my course in the fall 2016. The average overall score for these problems was 78%.

For problem 1b, I calculated the oxidation numbers using the familiar general chemistry method of assigning oxygen as –2 and hydrogen as +1. Students recently coming through organic may have some other way to do it, and you may need to provide directions for your students about your preferred method.  I think I could have worded part (c) better to try to emphasize the redox processes involved. I wanted them to think of combustion, but I think they needed to be specifically prompted, such as "Give an example of the combustion processes that generate CO2 and trace the oxidation state of carbon through the reaction." Overall my students scored 86% on problem 1.

The second problem (about another method that could be used to measure d-spacing) was fairly hit or miss.  Five students got full credit, six students got 3 points, and one got zero. Eleven out of twelve did answer part (a) correctly.  I realized as I made this LO that the article says the carbon-based material doesn’t diffract X-rays, but doesn’t actually directly explain whether or not the Cu nanoparticles diffracted X-rays, so you may need to adjust the question to be technically accurate.

Question three (re: surfactants in nanoparticle synthesis) referred back to knowledge from earlier in the course. The overall score was 61%.

Question 4 (define and describe electrodes) was fairly straightforward, and students scored 85%.

Question 5 caused some confusion, as some students missed that I was looking for “carbon-containing” products only. I didn’t count off for that mistake, but it made the problem harder for students who included hydrogen in each box.  Overall, students did very well on this problem (89% correct).

Question 6 – again, not too much trouble here (84% correct).

Question 7 – I was surprised that students didn’t do better on this question, as I thought that water reduction was mentioned often in the article.  Only three (of 12) students scored 5 points on this problem, and the average score was 53%.  This was probably my favorite question, as it foreshadows electrochemistry topics I cover in my inorganic course.

Description: 

This literature discussion is based on an article describing the use of copper nanoparticles on an N-doped textured graphene material to carry out the highly selective reduction of CO2 to ethanol (Yang Song et al., “High-Selectivity Electrochemical Conversion of CO2 to Ethanol using a Copper Nanoparticle / N-Doped Graphene Electrode” ChemistrySelect 2016, 1, 6055-6061.  DOI: 10.1002/slct.201601169). The article provides a good introduction to the concepts of electrochemical reduction, selectivity and recycling of fossil fuels. The literature discussion assignment shared here was used as half of the final exam in a half-credit nanomaterials chemistry course, but could be adapted for use as a take-home or in-class assignment.

Corequisites: 
Course Level: 
Learning Goals: 

After reading this paper and working through the problems, a student will be able to:

  • assign oxidation states to carbon and trace the oxidation and reduction of carbon through fossil fuel combustion and CO2 conversion
  • describe the role of control experiments in studying the CO2 conversion presented in the article
  • define the word “selective” in the context of this research
  • use the proposed mechanism to explain why the electrode studied produces ethanol in such a high proportion
  • identify the primary reaction competing with CO2 reduction for available electrons
Implementation Notes: 

These questions comprised half of the final exam for my half-credit nanomaterials chemistry course in the fall of 2016.  I gave the article to the students one week ahead of time. They were encouraged to read the article, make any small notes they liked, and meet with me in office hours with questions. At the final exam they were allowed to use their copy of the article, but they were also required to hand in their copy with their exam so that I could make sure they hadn't written lots of extraneous information on the exam copy.

The nanomaterials course features near-weekly homework assignments centered around articles from the literature. Because I used this article at the end of the course, students were already familiar with nanomaterials synthesis and characterization techniques. Thus, some of the questions I asked relied on previous knowledge. 

Please feel free to adapt these questions and add some of your own. Leave comments describing any new questions you’ve added.

Time Required: 
one hour
3 Mar 2017

In-class peer review

Submitted by S. Chantal E. Stieber, Cal Poly Pomona
Evaluation Methods: 

Student participation was evaluated during the in-class portion based on the questions students asked. 

The formal peer review homework was evaluated based on completion, level of thought and thoroughness.

Evaluation Results: 

Overall, students were very interested in this topic and had not formally learned about the process before. There was a very lively discussion and a lot of questions were asked. All students received full credit for participation. 

Similarly, once students received their classmate's paper for peer review, they took the process very seriously and carefully went through the paper and answered the worksheet questions. 

I was very impressed by the high quality of the formal peer reviews that were turned in as homework. Students clearly spent a lot of time to carefully think about the paper and craft a reasonable response. Most students received full-credit. 

Description: 

This activity includes questions for students to answer to help guide them through the process of peer review. It was designed to assist students in writing peer reviews for research reports written by their classmates, but could be applied to literature articles as well.

Corequisites: 
Prerequisites: 
Learning Goals: 

A student will be able to:

-Explain how the peer-review process works

-Critically read through a research article

-Carefully review a research article

-Write a professional peer review

Implementation Notes: 

An overview of peer review was given with three powerpoint slides. Students then worked through a modified Q&A of the peer review module "Peer Review - How does it work?" posted by Michael Norris on VIPEr. This provided students with an example of real reviews, along with the resulting article revisions. 

The current worksheet was then passed out to students along with a research report written by one of their classmates (I assigned these and removed names). In class, students answered the questions on the worksheet and were able to ask questions of the editor (the instructor in this case). Following the in-class peer review, students had to write a formal peer review, which was turned in as homework. 

The peer review was a final component of a research report that students had been working on throughout the course. The final report was turned in after students had received the review comments back from their peers. The grade of the final report took into consideration whether or not students had made modifications based on comments by their peer reviewer.

 
Time Required: 
60 min
4 Jan 2017
Description: 

This is a great new textbook by George Luther III from the University of Delaware.  The textbook represents the results of a course he has taught for graduate students in chemical oceanography, geochemistry and related disciplines.  It is clear that the point of the book is to provide students with the core material from inorganic chemistry that they will  need to explain inorganic processes in the environment.  However the material is presented in such a clear, logical fashion and builds so directly on fundamental principles of physical inorganic chemistry that the book is actually applicable to a much broader audience.  It provides a very welcome presentation of frontier orbital theory as a guide to predicting and explaining much inorganic chemical reactivity.  There are numerous very  helpful charts and tables and diagrams.  I found myself using the book for a table of effective nuclear charges when I was teaching general chemistry last semester.  The examples are much more interesting that the typical textbook examples and would be easy to embellish and structure a course around.  There is also a helpful companion website that provides powerpoint slides, student exercises and answers.  The book covers some topics not typically seen in inorganic textbooks like the acidity of solids but the presentation of this information makes sense in light of the coherent framework of the text.  We so often tell our students "structure dictates function".  This text really make good on that promise.  My only complaint is that I wish the title were something more generic so that I could use it for a second semester of introductory-esque material that we teach after students have taken a single semester of intro chem and two semesters of organic chemistry.  So much of what is covered in this textbook is precisely what a second semester sophomore chemistry major should know before proceeding on in the major.  But the title makes the book hard to sell to chemistry majors and that is regrettable. 

Prerequisites: 
Course Level: 
3 Jan 2017
Description: 

This Guided Literature Discussion was assigned as a course project, and is the result of work originated by students Stefanie Barnett and Katelyn Yowell.  It is based on the article “Synthesis, Electrochemistry, and Reactivity of Half-Sandwich Ruthenium Complexes Bearing Metallocene-Based Bisphosphines”, Shaw, A.P.; Norton, J.R.; Bucella, D.; Sites, L.A.; Kleinbach, S.S.; Jarem, D.A.; Bocage, K.M.; Nataro, C. Organometallics 2009, 28, 3804-3814. It includes a Reading Guide that will direct students to specific sections of the paper emphasized in the discussion.  This article presents the study of an array of metallocene-based bisphosphine ligands.

Course Level: 
Corequisites: 
Learning Goals: 

After reading and discussing this article, a student should be able to…

-       Understand the nomenclature of metallocene-based bisphosphine ligands.

-       Apply the CBC electron-counting method in the presence of metallocene-based bisphosphine ligands, which may be in an oxidized form.

-       Appreciate the role of phosphine cone angles in organometallic synthesis.

-       Understand the effect of a ligand’s electron donor ability on a metal’s redox potential.

-       Appreciate how synthetic methods may emphasize either the kinetic or thermodynamic product.

-       Understand how 1H NMR can help differentiate dihydride/dihydrogen isomers.

15 Dec 2016
Evaluation Methods: 

I had the students prepare for the discussion before class by reading the entire article. Students then answered the guiding questions in small groups during a class period.

I graded this assignment based upon class participation. All 33 students participated in the discussion. 

Evaluation Results: 

The average grade on this assignment was an A. Students very much enjoyed reading an article from the literature and connecting it to topics we discussed in class. This article opened up our discussion on catalysis and mechanisms. The article nicely describes the rational design of experiments to probe and catalytic reaction. 

Good paper to introduce kinetics and mechanistic studies.

Description: 

Reading and understanding a journal article is a critical skill to obtain as a student. After college, many students will pursue careers in which learning occurs exclusively from the literature. Students  will read a full paper from the journal Inorganic Chemistry and answer guiding questions pertaining to the article. There will be an in class discussion about the article to introduce which is used to introduce the topic of catalysis. This assignment breaks down the article through a series of questions that helps students to navigate a journal article.

Students will look copper complexes which catalyze atom transfer radical addition (ATRA) under sustainable means. 

The citation is Inorganic Chemistry 2012, 51, 11917-11929. 

Corequisites: 
Course Level: 
Prerequisites: 
Learning Goals: 
Students should be able to:
  1. Read a full journal article pertaining to organometallic chemistry
  2. Critically think about the chemical literature
  3. Read about and understand organometallic mechanistic and kinetic studies
  4. Determine that structural and electronic ligand modification influences the reactivity of catalysts
  5. Describe spectroscopic methods used to obtain rate constants
  6. Distinugish between coordinating and non-coordinating anions and effects on catalysis
  7. Define inner and outer spehere electron transfer and relate this to the proposed reaction mechanism
  8. Explain the mechanistic studies done to probe the lability of the TPMA ligand
Implementation Notes: 

I conducted this with a class of senior and junior chemistry majors and it went very well! This is a very long article so you could break this up into more basic topic and then more challenging ones.

Some of these questions could also be used on an exam. 

The questions are doable as students in the course actually helped develop these questions. I broke the article up into sections and assigned each section to a group of 4 students who were required to develop at least two questions per section. I then helped form the questions with the students. This model worked well and may be of interest to other people in the community.

But this assignment can be delivered as is - as a literature assignment with the focus on electron transfer, catalysis, mechanistic studies, and kinetics.

Time Required: 
50 minutes to 1 hour
30 Jun 2016
Evaluation Methods: 

This LO has not been implemented, however, we recommend a few options for evaluating student learning:

● implement as in class group work, collect and grade all questions

● have students complete the literature discussion questions before lecture, then ask them to modify their answers in another pen color as the in-class discussion goes through each questions

●  hold a discussion lecture for the literature questions; then for the following lecture period begin class with a quiz that uses a slightly modified problem analogous to question #6 or #8 where a comparison between two different complexes from the paper is proposed, students are asked to summarize differences in their experimental values of CO frequency and potential and chemical reasoning for these differences. 

Evaluation Results: 

This LO was created for the 2016 TUES workshop and has not yet been tested in the classroom.

Description: 

In this literature discussion, students read an Inorganic Chemistry paper (doi: 10.1021/ic503062w) about diarylamido-based PNZ pincer ligands and their Ni, Pd, and Rh complexes. Specifically, this paper uses IR and E1/2 potentials to demonstrate that the redox events occur not on the metal center but on the pincer ligands.  For these non-innocent ligands,  the electron donating ability of the pincer ligand towards the metal is more strongly influenced by the donors directly attached to the metal (phosphorus or nitrogen substituents) while the oxidation potential is more affected by the substituents on the diarylamine backbone.  This paper also provides x-ray crystallography data, NMR spectra (including J-coupling information), and a wealth of synthetic information.  This LO was created for the 2016 TUES Viper Workshop on organometallic chemistry.

Corequisites: 
Course Level: 
Learning Goals: 

In answering these questions, a student will…

●      Employ textual clues to define chemical terms such as pincer ligands

●      Apply CBC rules to count electrons for pincer-ligand containing complexes

●      Relate v(CO) stretching frequencies to electron donating abilities of ligands

●      Integrate prior knowledge of periodic trends and electrochemical data from the paper to refine their definition of non-innocent ligands.

●      Correlate electrochemical potential to the “electron richness” of the complex

Implementation Notes: 

Students should read the paper and complete the reading guide before the literature discussion. 

 We hope that instructors will mix and match questions that are appropriate to their classes.  In particular, instructors may want to be selective among the in-depth questions 5-19 depending on the desired emphasis.

 Summary:

Questions 1-4 assess scientific reading competency and foundational concepts, question 5-11 address fundamental inorganic topics related to changing electron density on the metal, wheras questions 12-19 require deeper discussion of ligand non-innocence and experimental methods to determine difference in electron richness.

Note: we envision question 4 being divided up among multiple groups with each group getting one of the rows.  Then, the instructor should highlight the fact that all complexes had the same values.

 

Time Required: 
1 class period
30 Jun 2016

Cyclic voltammetry animations

Submitted by George Lisensky, Beloit College
Evaluation Methods: 

This approach has been used for several years in an analytical course as preparation for a cyclic voltammetry lab experiment. 

Evaluation Results: 

Most students who have spent 20 minutes engaged with the material can interpret their cyclic voltammetry lab results.

Description: 

This is a question based approach for a discovery activity about cyclic voltammetry. The slider bar on a movie can used to control a variable and the displayed graph is updated to show the results. (You could also just play the movie to get an idea of what changes.)

The questions to be answered are

What is the shape of a cyclic voltammogram?

How are cyclic voltammograms affected by E0?

How are cyclic voltammograms affected by concentration?

How are redox equilibria affected by scan rate?

What if there are two reductions?

How are cyclic voltammograms affected by the electron transfer rate?

How are cyclic voltammograms affected by changing scan rate if the electron transfer is slow?

Corequisites: 
Prerequisites: 
Subdiscipline: 
Learning Goals: 

Students will understand how to interpret the shape of a simple cyclic voltammogram and the effects of redox potential, concentration, scan rate, and electron transfer rate.

Implementation Notes: 

This can be used in lecture or assigned as homework/reading.

Time Required: 
20 minutes
27 Jun 2016

Online Homework for a Foundations of Inorganic Chemistry Course

Submitted by Sabrina G. Sobel, Hofstra University
Evaluation Methods: 

Students are graded on a sliding scale based on the number of attempts on each question. An overall grade is assigned at the end of the semester, adjusted to the number of points allotted for the homework in the syllabus. 

Evaluation Results: 

Student performance on the overall homework assignments for the semester includes questions assigned on General Chemistry topics that are part of this class syllabus. 

 201420152016
Number404741
Average89%80%83%
S.D.15%19%23%

In addition to gethering data on overall  performance, I and my student assistants, Loren Wolfin and Marissa Strumolo, have completed a statistical study to assess performance on individual questions, and to identify problem questions that need to be edited. We identified two separate issues: incorrect/poorly worded questions, and assignment of level of difficulty. Five problematic questions were identified and edited. The level of difficulty was reassigned for eight questions rated as medium (level 2); six were reassigned as difficult (level 3), and two were reassigned as easy (level 1). I look forward to assessing student performance in Spring 2017 in light of these improvements. Please feel free to implement this Sapling homework in your class, and help in the improvement/evolution of this database.

Description: 

The Committee on Professional Training (CPT) has restructured accreditation of Chemistry-related degrees, removing the old model of one year each of General, Analytical, Organic, and Physical Chemistry plus other relevant advanced classes as designed by the individual department. The new model (2008) requires one semester each in the five Foundation areas: Analytical, Inorganic, Organic, Biochemistry and Physical Chemistry, leaving General Chemistry as an option, with the development of advanced classes up to the individual departments. This has caused an upheaval in the treatment of Inorganic Chemistry, elevating it to be on equal footing with the other, more ‘traditional’ subdisciplines which has meant the decoupling of General Chemistry from introduction to Inorganic Chemistry. No commercial online homework system includes sets for either Foundations or Advanced Inorganic Chemistry topics. Sapling online homework (www.saplinglearning.com) has been open to professor authors of homework problems; they have a limited database of advanced inorganic chemistry problems produced by a generous and industrious faculty person. I have developed a homework set for a semester­-long freshman/sophomore level Inorganic Chemistry course aligned to the textbook Descriptive Inorganic Chemistry by Rayner-Canham and Overton (ISBN 1-4641-2560-0, www.whfreeman.com/descriptive6e ), and have test run it three times. Question development, analysis of student performance and troubleshooting in addition to topic choices, are critical to this process, especially in light of new information about what topics are taught in such a course (Great Expectations: Using an Analysis of Current Practices To Propose a Framework for the Undergraduate Inorganic Curriculum: http://pubs.acs.org/doi/full/10.1021/acs.inorgchem.5b01320 ).This is an ongoing process, and I am working to improve the database all the time.

Prerequisites: 
Corequisites: 
Course Level: 
Learning Goals: 

1.      Increase understanding in these topic areas:

a.      Acid-base chemistry and solvent systems

b.      Bonding models of inorganic molecules and complexes

c.      Bonding models in extended systems (solids)

d.      Descriptive chemistry and Periodic Trends

e.      Electronic structure of inorganic molecules, complexes and solids

f.       Extended structures: unit cells and other solid-state structural features

g.      Molecular structure and shape of inorganic molecules

h.      Inorganic Complexes nomenclature, bonding and shapes

i.       Redox chemistry and application to inorganic systems

j.       Thermodynamics as applied to inorganic solids and inorganic systems

2.      Practice using knowledge in these topic areas:

a.      Acid-base chemistry and solvent systems

b.      Bonding models of inorganic molecules and complexes

c.      Bonding models in extended systems (solids)

d.      Descriptive chemistry and Periodic Trends

e.      Electronic structure of inorganic molecules, complexes and solids

f.       Extended structures: unit cells and other solid-state structural features

g.      Molecular structure and shape of inorganic molecules

h.      Inorganic Complexes nomenclature, bonding and shapes

i.       Redox chemistry and application to inorganic systems

j.       Thermodynamics as applied to inorganic solids and inorganic systems

Implementation Notes: 

The database of homework questions is available through Sapling Learning. They can be implemented as an online homework set for a class. Students need to buy access to the Sapling online homework for the duration of the class, typically $45.

Time Required: 
variable

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