Introductory Chemistry

8 Apr 2020

Electrochemistry: Galvanic Cells and the Nernst Equation

Submitted by William Polik, Hope College
Evaluation Methods: 

The completed worksheets were graded on a 50 point scale with 10 points/question.

Evaluation Results: 

Results for one lab section:

Average score was 40.8/50 points

Students frequently neglected to put units on their results. Up to three points were taken off for this (one for the first instance, one for the slope of their Nernst equation, and one for the molarity of their unknown).

Most students were not able to calculate the concentration of their unknown solution (4D). Some were able to find Q, but did not realize that they needed to substitute "1 M" for "Right Conc" and then solve for "Left Conc." (-2)

At least two students swapped their slope and intercept in the unknown concentration calculation (4D). (-2)

Many students did not include an electrochemical reaction in the final "application" question, but most included a citation! (-2)

Most of these problems can be addressed in the next iteration of the instruction.

Description: 

In this online Electrochemistry Experiment, students use an Electrochemical Cell Simulator to construct electrochemical cells, measure voltages, and interpret results.

 
Corequisites: 
Prerequisites: 
Course Level: 
Learning Goals: 
  1. Students will write balanced redox (reduction and oxidation) reactions.

  2. Students will calculate cell voltages under standard solution concentration conditions for a galvanic cell.

  3. Students will use the Nernst Equation to calculate electrochemical cell voltages under non-standard solution concentration conditions for a galvanic cell.

  4. Students will use the Nernst Equation to create a graph for a concentration cell and use the slope and intercept to find the concentration of an unknown (given its cell potential).

Topics Covered: 
Equipment needs: 

This experiment relies upon the Electrochemical Cells simulator available at

http://web.mst.edu/~gbert/Electro/Electrochem.html

written by Dr. Gary L. Bertrand at the University of Missouri-Rolla.

 
Implementation Notes: 

This lab was developed during the COVID-19 crisis to replace our normal in-person general chemistry lab. All resources were shared with students in the course management system. 

Students watch two videos, one about electrochemistry concepts (our students had not seen electrochemistry in lecture yet) and the other about the operation of the simulator. [Note: Videos are posted as "Faculty-only Files."]

Students make a copy of the Electrochemistry Lab Template (as a Google Doc), which guides them through the experiment. (Note: We put a link to the Google Doc of the Template in our course management system. It was set up so that when they clicked on the link, it automatically made a copy of the Google Doc for them.) Following the instructions in the Template, they run experiments on the Simulator and record their results in the Template. They also do some calculations in the Template.

When they have completed the tasks outlined in the Template, they export the document as a pdf and upload the pdf file to the course management system.

Laboratory materials were posted to all general chemistry laboratory sections on a Monday morning. Students met briefly (synchronously) with their laboratory sections during the first week to clarify expectations. During the second week, there were optional lab meetings so that students could get any questions answered. The completed laboratory template was due Friday of the second week.

Time Required: 
One-two weeks *see note in implementation on timing
2 Mar 2020

ChemCrafter

Submitted by Michelle Personick, Wesleyan University
Evaluation Methods: 

Student learning is not assessed directly after the activity, but rather is assessed indirectly through student performance on related homework and exam questions. More specifically, the second section of the exams in my general chemistry course always asks students to "provide a concise (but complete) explanation or rationalization for [some number] of the following statements." This section is particularly suited to assessing the learning goals above.

Evaluation Results: 

This activity was recently introduced, and student performance has not been evaluated yet.

Description: 

ChemCrafter, from the Science History Institute (formerly the Chemical Heritage Foundation), is a free iPad app that mimics a classic chemistry set. It is set up as a game, with three sections: reactions with water, reactions with acid, and salts. The app shows the progress of the reaction (smoke, color change, etc.) when two elements are mixed in a reaction vessel, and also gives the change in enthalpy of the reaction.

Pros: It's a safe and fun way to demonstrate some visually exciting chemical reactions. It's free and the graphics are high quality. The app projects well on a large screen using a standard classroom projector.

Cons: Accessing later sections of reactions requires completion of the previous sections, and there is some artificial gating of chemical and glassware replenishment behind wait times. As a result, it's best used as a demo rather than as a dry lab. It's also only available for the iPad.

 

Prerequisites: 
Corequisites: 
Course Level: 
Learning Goals: 

Students should be able to explain the difference between thermodynamics and kinetics.

Students should be able to explain why even thermodynamically favorable reactions sometimes do not proceed on an observable timescale.

Students should be able to explain why heat is sometimes necessary to make a highly exothermic reaction proceed.

Implementation Notes: 

Once everything is unlocked, it's possible to set up any reaction using the chemicals in the given "set" for each category of reaction. I use ChemCrafter in my second semester general chemistry course to transition from a unit on reactions of ions in aqueous solution (hydration/hydrolysis, Bronsted acid/base and hard-soft acid base principles of solubility/reactivity, etc.) to a unit on kinetics. I show a series of reactions from the salt section that the students would expect to have roughly increasing enthalpies of lattice formation based on the Born-Lande equation:

[Note: All reactants are in their elemental form in the app, so the enthalpies of formation aren't truly lattice energies.]

2 Na + Cl2 --> 2 NaCl   (1+ cation with a 1- anion) 

2 K + F2 --> 2 KF (1+ cation with a 1- anion)

Zn + Cl2 --> 2 ZnCl(2+ cation wtih a 1- anion)

These combinations were selected because their reactions in the app become increasingly dramatic (and colorful) in this order. I then show the students a set of reactions that they would expect to be even more exciting, but which don't actually proceed without heat. They hold their breath for the first one to react.

Zn + S --> ZnS (2+ cation with a 2- anion)

2 Al + 3 I2 --> 2 AlI3 (3+ cation with a 1- anion)

The app provides an option for heating these mixtures of elements with a bunsen burner, and then they react dramatically. At this point, we're ready to discuss the difference between thermodynamics--which is all they've seen up to this point--and kinetics.

Time Required: 
5-10 minutes of class time
20 Feb 2020

Cisplatin and Anticancer Therapy: The Role of Chemical Equilibrium

Submitted by Jack F Eichler, University of California, Riverside
Evaluation Methods: 

1) Performance on the pre-lecture online quiz

2) Performance on the in-class activity (clicker scores or hand-graded worksheet)

Evaluation Results: 

Students generally score on average 70% or higher on the pre-lecture quiz, and on average 70% or more of students correctly answer the in-class clicker questions. 

Description: 

This is a flipped classroom module that covers the concept of dynamic equilibrium, and how dynamic equlibrium plays a role in the anticancer mechanism of the therapeutic cisplatin.This activity is designed to be done at the end of the typical second quarter/second semester general chemistry equilibrium unit. Students will be expected to have learned the following concepts prior to completing this activity:

a) understanding the concept of dynamic equilibrium;

b) understanding how equilibrium expressions are generated for chemical reactions that include aqueous solutions, gas phase reactants/products, and/or heterogeneous reactions;

c) understanding how to calculate the molarity of a solution and how to carry out basic stoichiometric conversions for chemical reactions.

Acknowledgement: This material is based upon work supported by the National Science Foundation under Grant No. 1504989. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

 

 

Learning Goals: 

Students are expected to achieve the following learning objectives:

a) using ICE tables to calculate the equilibrium concentration of reactants and/or products;

b) using ICE tables and stoichiometric calculations to predict what initial concentration of reactant would be required to yield a specific concentration of product at equilibrium;

c) understanding the concept of Le Chatelier’s principle and how equilibrium reactions will respond to changes in concentration of reactant and/or product;

d) being able to calculate the reaction quotient (Q), and relating the reaction quotient to explain whether a reaction has reached dynamic equilibrium or not.

e) connecting the concept of chemical equilibrium to the real-world application of anticancer therapeutics and how the drug cisplatin imparts tumor cell death.

 

Topics Covered: 
Corequisites: 
Course Level: 
Prerequisites: 
Implementation Notes: 

See attached instructor notes. 

Time Required: 
50-80 minutes
16 Jan 2020

Time-Integrated Rate Laws and the Stability of Gold(III) Anticancer Compounds

Submitted by Jack F Eichler, University of California, Riverside
Evaluation Methods: 

1) Performance on the pre-lecture online quiz

2) Performance on the in-class activity (clicker scores or hand-graded worksheet)

 

Evaluation Results: 

Students generally score on average 70% or higher on the pre-lecdure quiz, and on average 70% or more of students correctly answer the in-class clicker questions. 

Description: 

This is a flipped classroom module that covers the concepts of time-integrated rate laws. This activity is designed to be done at the end of the typical second quarter/second semester general chemistry kinetics unit. Students will be expected to have learned the following concepts prior to completing this activity:

a) how instantaneous rates of reactions are determined by measuring changes in concentration of reactants and/or products at the beginning of the reaction;

b) understanding basic rate laws and how rate laws are determined for a chemical reaction using instantaneous rates;

c) understanding why the rates of reactions slow down as the time of reaction increases.

Acknowledgement: This material is based upon work supported by the National Science Foundation under Grant No. 1504989. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

 

Learning Goals: 

Students are expected to achieve the following learning goals:

a) conceptually understand how time-integrated rates laws can be used to describe the kinetics of a chemical reaction;

b) use time-integrated rate laws to determine the rate constant for a first or second order reaction;

c) use time-integrated rate laws to determine the half-life of a decomposition reaction;

d) use Excel to plot time-integrated rate laws and generate best-fit linear trend lines.

 

Corequisites: 
Equipment needs: 

Students need a laptop or tablet device capable of operating a spreadsheet/graphing program. 

Course Level: 
Prerequisites: 
Topics Covered: 
Subdiscipline: 
Implementation Notes: 

See attached instructor notes. 

Time Required: 
50-80 minutes
2 Jan 2020

Reaction Mechanisms: Energy Profiles and Catalysts

Submitted by Wesley S. Farrell, United States Naval Academy
Evaluation Methods: 

Students will report answers to the class.  The instructor should use the quality of these responses to gauge understanding.

Evaluation Results: 

N/A

Description: 

This in class activity consists of two demonstrations to be performed by the instructor, followed by a worksheet that students may work on independently or in groups.  The demonstrations allow the students to determine when a reaction has occured, when it has not occured, and generate qualitative reaction energy profiles to match these observations.  This activity is designed to take place during a description of kinetics in general chemistry. Detailed descriptions of the procedure and activity may be found in the "Overview for Instructor."

Learning Goals: 

Students should be able to create qualitative reaction energy profiles which match a series of reactions, catalyzed and uncatalyzed.

Subdiscipline: 
Equipment needs: 
  • Three 8” test tubes
  • 3% H2O2
  • Small cubes of potato, both raw and cooked
  • 250 mL Erlenmeyer flask
  • Pt spiral (preferably in glass tube with hook for support)
  • Methanol
  • Bunsen burner (with striker)

 

Course Level: 
Corequisites: 
Prerequisites: 
Topics Covered: 
Implementation Notes: 

Please see the "Overview for Instructor" document for implementation notes.

Time Required: 
15 minutes
5 Dec 2019

Flipped Class Module - Lewis Structures of Industrially and Environmentally Relevant Molecules

Submitted by Jack F Eichler, University of California, Riverside
Evaluation Methods: 

1) Performance on the pre-lecture online quiz

2) Performance on the in-class activity (clicker scores or hand-graded worksheet)

 

Evaluation Results: 

Students generally score on average 70% or higher on the pre-lecdure quiz, and on average 70% or more of students correctly answer the in-class clicker questions. 

Description: 

This is a flipped classroom activity intended for use in a first semester general chemistry course. Students are expected to have prior knowledge in identifyng the difference between molecular and ionic compounds, understanding the conceptual framework for how covalent bonds form, and how to draw Lewis dot symbols for atoms, and how to determine the number of valence electrons for atoms.



The activity includes:

1) pre-lecture learning videos that guide students through learning how to draw valid Lewis structures, determining how to caculate the formal charge for atoms in molecular compuonds/Lewis structures, and using formal charge to determine which Lewis structure is most stable if multiple Lewis structures are possible for a given molecule;

2) pre-lecture quiz questions; and

3) an in-class activity that requires students to apply their knowledge of chemical bonding in drawing Lewis structures.

Acknowledgement: This material is based upon work supported by the National Science Foundation under Grant No. 1504989. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Learning Goals: 

Students should be able to:

a) draw Lewis structures of molecular compounds;

b) determine the formal charge of atoms in molecular compounds;

c) use formal charge to predict the most stable Lewis structure.

 

Equipment needs: 

Suggested technology:

1) online test/quiz function in course management system

2) in-class response system (clickers)

Course Level: 
Corequisites: 
Prerequisites: 
Implementation Notes: 

Attached as separate file. 

Time Required: 
50-80 minutes
18 Jul 2019

Science Information Literacy Badge--Reading the Literature

Submitted by Michelle Personick, Wesleyan University
Evaluation Methods: 

I use this activity as a "badge," which is self-paced guided skill-building activity that students complete on their own time outside of class. Badges are designed around fundamental chemistry skills that students wouldn’t necessarily acquire from standard course content and lectures. They carry a very small point value (about 2% of the course total per badge) but my students are very motivated by even small amounts of points. I assign points primarily based on completion and effort and also provide brief written feedback for each student. I have my students turn in badges in Moodle, which makes feedback more streamlined.

Description: 

This is an activity designed to introduce general chemistry students to reading the chemistry literature by familiarizing them with the structure of a published article. The activity first presents an article from the Whitesides group at Harvard about writing a scientific manuscript, along with a video about the peer-review process. There are two parts to the questions in the activity, which are based on a specific article from Nature Communications (doi.org/10.1038/s41467-019-08824-8). Part I is focused on the structure of the article and where to find key pieces of information. Part II encourages students to use general audience summaries in combination with the original article to best understand the science while making sure they get a complete and accurate picture of the reported work.

Prerequisites: 
Course Level: 
Corequisites: 
Learning Goals: 

A student should be able to approach the chemistry literature and determine where to find:

  • the authors and their affiliations;
  • the main objective of the research;
  • the main outcomes of the research;
  • why the research is important;
  • experimental details;
  • supplementary figures and other information. 

A student should be able to broadly evaluate the reliability of secondary summaries of scientific articles by comparing them against the key points of the original paper.

Implementation Notes: 

This activity is based on a specific article: "Room temperature CO2 reduction to solid carbon species on liquid metals featuring atomically thin ceria interfaces" (Nat. Commun., 2019, 10, 865. doi.org/10.1038/s41467-019-08824-8). However, it's easily adapted to other articles that are more suited to a particular course, and I've used other articles in previous iterations. This article was chosen because the content is at least partly accessible to students in my second semester general chemistry course, who have already had some electrochemistry/redox chemistry, and who have recently learned about kinetics, reaction mechanisms, and catalysis. The topic of liquid metals is new and interesting to the students, because it's not something the'd normally be exposed to, and the application to CO2 sequestration is something they can connect with. 

 

9 Jul 2019

Constructing a Class Acid-Base Titration Curve

Submitted by Katherine Nicole Crowder, University of Mary Washington
Evaluation Methods: 

Students were allowed to keep working until they had correct pH values, so they were graded on participation. Worksheets were collected at the end in order to construct the titration curve.

This could be collected and graded for correctness.

 

Evaluation Results: 

Students were evaluated on similar questions on the subsequent exam. Most students (12 out of 15) scored 11-13 points on a 13 point question where they had to solve for the pH in the four regions of a strong acid titration curve. 8 out of 15 recieved full credit on a question where they had to calculate the pH in the buffer region of a weak acid titration curve.

Description: 

In this in-class activity, each student calculates the inital pH, equivalence volume, and pH at the equivalence point for both a strong acid-strong base and a weak acid-strong base titration.

In addition, each student is assigned a unique volume before the equivalence point and a unique volume after the equivalence point for each titration curve.

The data from the class is then assembled in Excel to construct the two titration curves.

This forces each student to do the calculations for each of the four regions of both types of titration curves. This activity could be used to introduce titration curves or to reinforce previously covered lecture material/problem-solving. It could also be switched to do a strong base-strong acid or a weak base-strong acid titration curve.

The constructed titration curves can be used for further discussions of the differences between a strong acid and a weak acid in terms of initial pH, the rapid-rise portion of the curve, and the pH at the equivalence point.

 

 

Learning Goals: 

A student should be able to

  • determine the pH of a strong acid solution
  • determine the pH of a weak acid solution using Ka
  • use stoichiometry to calculate equivalence volumes for acid-base titrations
  • employ limiting reagent calculations to determine acid or base concentrations for different regions of a titration curve and determine pH
  • determine the pH of a weak base solution using Ka, Kb
Subdiscipline: 
Equipment needs: 

notecards with assigned volumes

computer for entering volume and pH data

Course Level: 
Corequisites: 
Prerequisites: 
Topics Covered: 
Implementation Notes: 

This could be done as an in-class activity (I used a 3 hr lab period - most students took less than 2 hrs) or as a take-home assignment. Students were allowed to use their notes and textbooks. I did not strictly forbid them from working together, but I did tell them that I wanted them to be sure that they could do all of the calculations themselves.

I had an Excel spreadsheet of the correct pH values for each volume (attached). Students were allowed to come check their work with me and continue working if their answers were incorrect. I was also able to help them if they got stuck.

 

Attached are the student worksheets, the class titration curves, and the Excel file I used to calculate the correct pH values. I chose volumes and molarities that would give me an appropriate number of volumes before the equivalence point. Volumes and molarities should be adjusted as needed for the size of your class.

I used whole number volumes, but I think it would be better to have smaller volume increments near the rapid-rise portions of the curves so it doesn't look like the data "jumps" as much.

Time Required: 
1-2 hr
8 Jun 2019

VIPEr Fellows 2019 Workshop Favorites

Submitted by Barbara Reisner, James Madison University

During our first fellows workshop, the first cohort of VIPEr fellows pulled together learning objects that they've used and liked or want to try the next time they teach their inorganic courses.

8 Jun 2019

IUPAC Brief Guide to the Nomenclature of Inorganic Chemistry

Submitted by Robin Macaluso, University of Texas Arlington
Description: 

This is a short nomenclature guide designed to be used by students and faculty.

Subdiscipline: 
Topics Covered: 
Prerequisites: 
Corequisites: 

Pages

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