First year

19 Dec 2017

Visual scaffold for stoichiometry

Submitted by Margaret Scheuermann, Western Washington University
Description: 

These five slides are intended to share a visual scaffolding that I developed to help my general chemistry students identify what calculations are needed to solve stoichiometry problems.

 

The visual scaffold involves writing the balanced equation and then under it drawing a table with two rows and enough columns so that there is one column under each reagent in the equation. The top row is labeled as "moles" and the bottom row is labeled as "measurable quantity". Students then write in any information about a specific reagent or product that was given and identify the quantity that the question is asking them to find. They then add a series of arrows to the table to generate a "map" of how to get from the information they are given to the information they need to find with each arrow representating a type of calculation that they have already seen and practiced. Vertical arrows represent a calculation between a measured quantity and a number of moles. Horizontal arrows in the top row represent calculations between moles of one substance and moles of another substance. Horziontal arrows in the "measured quantity" row are not allowed since those unit conversion factors are not readily available. 

 

Corequisites: 
Topics Covered: 
Prerequisites: 
Course Level: 
Learning Goals: 

A student should be able to determine the quantity of a reagent required or the quantity of a product produced in a reaction.

Subdiscipline: 
Related activities: 
Implementation Notes: 

The scaffolding begins with a review of the two types of calculations that are required for basic stoichiometry: converting between grams and moles, and converting between moles of one substance and moles of another substance using the coefficients of a balanced equation as unit conversion factors (slide 1).

Some ABCD card/clicker questions can be added here if students have not practiced these types of problems in class recently.

After introducing the visual scaffold (slide 2) I do an example problem or two on the board/overhead/doc cam (slide 3).

This is a good point to give students an opportunity to work on a practice problem or if the introduction to stoichiometry began part way through a class period, an exit question.

Next I introduce situations where it could take more than one calculation to get from the measured quantity to moles (slide 4). 

An example problem and/or practice problem and/or exit question can be added here.

The visual scaffold is also relevant for limiting reagent problems. I've included an example (slide 5/6) but limiting reagent is usually presented in a subsequent class period after some examples of the limiting reagent concept using sandwiches or something similar. 

Time Required: 
30-50 minutes. varies with the number of examples and practice problems
Evaluation
Evaluation Methods: 

I will usually do an exit question- a stoichiometry problem from the textbook- after either slide 3 or slide 4. I do not require students to use the visual scaffold if they are already comfortable with stoichiometry from a previous class but many choose to use it. Some students will include the tables from the visual scaffold as part of the work they show on exams, again without being prompted or required to do so. 

31 Jul 2017

Inorganic Nomenclature: Naming Coordination Compounds

Submitted by Gary L. Guillet, Georgia Southern University Armstrong Campus
Evaluation Methods: 

For my course I grade this assignment as a problem set.  Upon collecting the assignment I do not exhaustively grade them.  I check them over for completness.  I tell the students when I hand it out that it is designed for them to learn and then test their own comprehension and if they are stuck they should bring issues to office hours. 

On the following exam I put two or three inorganic complex names and have the students draw the structures.  The test questions always incorporate isomerism in addition to combinations of common ligands and transition metals.

Evaluation Results: 

After completion of this assignment most students are able to draw straigthforward structures including some isomers on an exam.  They can identify common ligands from their names like water, ammonia, carbon monoxide.  They also understand the common conventions in naming including handling cis and trans isomers as well as fac and mer isomers.

In the most recent sample of ACS examinations (IN16D) 87% of my students answerd correctly on the question most directly related to this assignment, selecting the correct name of a given complex using a picture of the complex.  I do not have any comparative data from another teaching approach.

Description: 

I do not like to take a large amount of time in class to cover nomenclature of any kind though I want students to know the names of common ligands and the basic ideas of how coordination complexes are named.  Since it is a systematic topic I assign this guided inquiry worksheet.   The students complete it outside of class and can work at whatever pace they want.  If they are more familiar with the topics the can quickly complete it but if they are rusty or have not seen some of the material it gives them an easy entry point to ask questions to fill in any gaps in their knowledge.  This assignment covers determing charge on a metal in a complex with simple ligands, how to identify and name common isomers, and it is structured in a guided inquiry form. 

Learning Goals: 

Students will be able to identify and correctly name common ligands in a chemical structure or chemical name.

Students will be able to identify the charge on a metal or a ligand in a chemical structure.

Students will be able to identify common isomeric differences in a chemical structure or a chemical formula (cis, trans, fac, mer). 

Students will be able to use a chemical name to draw a chemical structure.

Equipment needs: 

None

Topics Covered: 
Corequisites: 
Prerequisites: 
Implementation Notes: 

I use this assignment to replace a lengthy lecture on the topic of nomenclature when covering coordination chemistry.  I have students complete this assignment outside of class.  I encourage them to work in pairs so students can jointly interpret the instructions and determine the patterns in naming complexes.  The assignment is constructed in a very straightforward manner and covers the basics of inorganic nomenclature.

Upon completion of the assignment I take about 15-20 minutes in class to quickly cover the main ideas of the assignment.  I field any questions that arose during the assignment and I do a few comprehension check type questions on the board. 

Time Required: 
1-2 hours
3 Jun 2017

Literature Discussion of "A stable compound of helium and sodium at high pressure"

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

Students could be evaluated based on their participation in the in-class discussion or on their submitted written answers to assigned questions.

Evaluation Results: 

This LO has not been used in a class at this point. Evaluation results will be uploaded as it is used (by Spring 2018 at the latest).

Description: 

This paper describes the synthesis of a stable compound of sodium and helium at very high pressures. The paper uses computational methods to predict likely compounds with helium, then describe a synthetic protocol to make the thermodynamically favored Na2He compound. The compound has a fluorite structure and is an electride with the delocalization of 2e- into the structure.

This paper would be appropriate after discussion of solid state structures and band theory.

The questions are divided into categories and have a wide range of levels.

Dong, X.; Oganov, A. R.; Goncharov, A. F.; Stavrou, E.; Lobanov, S.; Saleh, G.; Qian, G.-R.; Zhu, Q.; Gatti, C.; Deringer, V. L.; et al. A stable compound of helium and sodium at high pressure. Nature Chemistry 2017, 9 (5), 440–445 DOI: 10.1038/nchem.2716.

Corequisites: 
Learning Goals: 

After reading and discussing this paper, students will be able to

  • Describe the solid state structure of a novel compound using their knowledge of unit cells and ionic crystals
  • Apply band theory to a specific material
  • Describe how XRD is used to determine solid state structure
  • Describe the bonding in an electride structure
  • Apply periodic trends to compare/explain reactivity
Implementation Notes: 

The questions are divided into categories (comprehensive questions, atomic and molecular properties, solid state structure, electronic structure and other topics) that may or may not be appropriate for your class. To cover all of the questions, you will probably need at least two class periods. Adapt the assignment as you see fit.

CrystalMaker software can be used to visualize the compound. ICE model kits can also be used to build the compound using the template for a Heusler alloy.

Time Required: 
2 class periods
3 Jun 2017
Evaluation Methods: 

This LO was craeted at the pre-MARM 2017 ViPER workshop and has not been used in the classroom.  The authors will update the evaluation methods after it is used.

Description: 

This module offers students in an introductory chemistry or foundational inorganic course exposure to recent literature work. Students will apply their knowledge of VSEPR, acid-base theory, and thermodynamics to understand the effects of addition of ligands on the stabilities of resulting SiO2-containing complexes. Students will reference results of DFT calculations and gain a basic understanding of how DFT can be used to calculate stabilities of molecules.

 
Prerequisites: 
Corequisites: 
Learning Goals: 

Students should be able to:

  1. Apply VSEPR to determine donor and acceptor orbitals of the ligands

  2. Identify lewis acids and lewis bases

  3. Elucidate energy relationships

  4. Explain how computational chemistry is beneficial to experimentalists

  5. Characterize bond strengths based on ligand donors

Course Level: 
Implementation Notes: 

Students should have access to the paper and have read the first and second paragraphs of the paper. Students should also refer to scheme 2 and table 2.

 

This module could be either used as a homework assignment or in-class activity. This was created during the IONiC VIPEr workshop 2017 and has not yet been implemented.

 
Time Required: 
50 min
3 Jun 2017
Evaluation Methods: 

This was created during the IONiC VIPEr workshop 2017 and has not yet been implemented.

 
Description: 

This module offers students an introductory chemistry or foundational inorganic course exposure to recent literature work. Students will apply their knowledge of VSEPR and basic bonding to predict geometries of complex SiO2-containing structures. Students will gain a basic understanding of how crystallography is used to determine molecular structures and compare experimental crystallographic data to their predictions.

Prerequisites: 
Course Level: 
Corequisites: 
Learning Goals: 

Students will be able to:

  1. Describe the bonding in SiO2 and related compounds
  2. Apply bonding models to compare and contrast bond types
  3. Apply VSEPR to predict bond angles
  4. Utilize crystallographic data to evaluate structures
Implementation Notes: 

Students should have access to the paper and read the first and fourth paragraphs on the first page and the third paragraph on the second page. Students should also reference scheme 1 and figure 1.

 

This module could be either used as a homework assignment or in-class activity.

 
3 Jun 2017
Evaluation Methods: 

This learning object was created at the pre-MARM workshop in 2017 and as such has not been used in a classroom setting. The authors will update the learning object once they have used it in their classes.

Description: 

This module offers students in an introductory chemistry or foundational inorganic course exposure to recent literature. Students will apply their knowledge of Lewis dot structure theory and basic thermodynamics to compare and contrast bonding in SiO2 and CO2.

Corequisites: 
Course Level: 
Prerequisites: 
Learning Goals: 

Students should be able to:

  1. Describe the bonding in SiO2 and related compounds (CO2)

  2. Use Lewis dot structure theory to predict bond orders

  3. Apply bonding models to compare and contrast bond types and bond energies (sigma, pi)

  4. Characterize bond strengths based on ligand donors

Implementation Notes: 

Students should read the first paragraph of the paper prior to completing this learning object. They can be encouraged to read more of the paper, but the opening paragraph is the focus of this learning object.

Time Required: 
50 min
26 Mar 2017

Formulas and Nomenclature of Compounds

Submitted by Sarah Shaner, Southeast Missouri State University
Evaluation Methods: 

The activity was not graded. After students work through the problems in pairs, we come back together as a class and discuss any problems that caused the students trouble.

Description: 

Students will be given the formula for a cation or anion on a slip of paper or index card. He or she will find another student with an ion with the opposite charge and practice writing the formula and naming the ionic compound that would result by combining the cation and anion. Students also answer a few questions about naming and formulas of binary molecular compounds with their partner.

Learning Goals: 
  • Become better acquainted with their classmates and get used to working in groups.
  • Construct formulas for ionic compounds based on ion charges.
  • Practice naming ionic and molecular compounds based on their formulas.
Corequisites: 
Prerequisites: 
Equipment needs: 

The instructor will need scissor and/or index cards to prepare the slips of paper or cards with ion names on them.

Topics Covered: 
Course Level: 
Subdiscipline: 
Implementation Notes: 

I typically give cations to one half of the room and anions to the other half. This means that students must move around the room to find a suitable partner. Since this is early in the semester, this helps with getting students to talk and work with people in the class they may not know.

Time Required: 
About 20 minutes
25 Mar 2017

KINETICS - Computations vs. Experiment

Submitted by Teresa J Bixby, Lewis University
Evaluation Methods: 

- determine the activation energy of a reaction from an energy diagram

- determine the rate constant for the reaction from the activation energy

- determine the rate law and rate constant for a reaction from experimental data

 

These Learning Objectives will be assessed on a subsequent exam.

Evaluation Results: 

Most students did not have a problem determining the rate constant from the activation energy (from an energy diagram). From what mistakes there were, the most common mistake was choosing the wrong starting energy (choosing the product energy rather than the reactant energy to start). Most students were also able to determine the rate constant from experimental data, especially if there were clearly 2 experiments where only one reactant concentration was doubled for each reactant. Changing the factor by which the reactant concentration changed (1.3 for example), or including experimental data where two reactant concentrations changed at the same time, seemed to cause more problems. 

Description: 

<p>This activity has students use Spartan to build an energy diagram for an SN2 reaction as a function of bond length. The activation energy can then be used to determine the rate constant for the reaction. After a few intoductory questions to orient general chemistry students to the organic reaction (with a short class discussion), the instructions lead them step-by-step to build the energy diagram for CH&lt;sub&gt;3&lt;/sub&gt;Cl + Cl- --&gt; Cl- + CH&lt;sub&gt;3&lt;/sub&gt;Cl. Any questions about how to use the program or descriptions of the levels of theory are given during the class period. The questions, class discussion, and Spartan tutorial for the first reaction can be compelted in one 50 min period.&nbsp;</p><p>The rest of the activity is completed as an assignment. Other anions attack CH&lt;sub&gt;3&lt;/sub&gt;Cl and students consider which product is more stable. They also compare the computational rate constant for OH- attacking with a rate constant determined from experimental data. They find that Spartan is good for molecular modeling but the absolute value of the energies of the transition states are inaccurate.&nbsp;</p><p>SN2 reactions with more complex molecuels may be more illustrative.&nbsp;</p><p>In the future we hope to develop this activity into an in-class prelab where then students can collect the experimental data on their own.&nbsp;</p>

Learning Goals: 

- use Spartan to build molecules and a transition state

- determine the activation energy of a reaction from an energy diagram

- determine the rate constant for the reaction from the activation energy

- determine the rate law and rate constant for a reaction from experimental data

- relate reactant and product energies to leaving group character

- compare computation to experiment

Prerequisites: 
Corequisites: 
Equipment needs: 

Need to have access to Spartan Student.

Topics Covered: 
Course Level: 
Subdiscipline: 
Implementation Notes: 

Building the transition state seems to be the most confusing part for General Chemistry students who have not used Spartan before. Encouraging them to limit twirling the molecule around a lot before they have completed this step seems to help. I intend to clarify these instructions before the next implementation. 

A different base molecule may yield better agreement with experimental data. This will aslo be explored before the next implementation.

Time Required: 
50 min + out-of-class assignment (~5 days)
2 Mar 2017

Experimenting with Danger- CSB safety Video

Submitted by Sheila Smith, University of Michigan- Dearborn
Description: 

This 2011 video by the Chemical Safety Board is a very serious and moving motivation for adopting safe practices in the chemical laboratory.  It focuses on two recent and very real safety issues in University labs (UCLA, 2008 and TTU, 2010 ), both of which have shaken the educational research community to result in positive change. 

I have shared a "SafeShare" link so that you will not have to listen to ads, and if you choose to play the link in your classroom, you will not see all the Youtube ads on the screen.  

Prerequisites: 
Corequisites: 
Learning Goals: 

Students will gain a real sense of the importance of chemical safety in the laboratory that is related to real people who have suffered real losses.  

Implementation Notes: 

I will be using this video as part of my standard safety training during intake of new undergraduate researchers in my research lab and in the first week of Advanced lab.

I will also be working to get our general chemistry coordinator to adopt some or all of it as part of the lab safety training for freshmen.

Time Required: 
24 minutes
18 Jan 2017

calistry calculators

Submitted by Adam R. Johnson, Harvey Mudd College
Description: 

I just stumbled on this site while refreshing myself on the use of Slater's rules for calculating Zeff for electrons. There are a variety of calculators on there including some for visualizing lattice planes and diffraction, equilibrium, pH and pKa, equation balancing, Born-Landé, radioactive decay, wavelengths, electronegativities, Curie Law, solution preparation crystal field stabilization energy, and more.

I checked and it calculated Zeff correctly but I can't vouch for the accuracy of any of the other calculators. 

Prerequisites: 
Corequisites: 
Learning Goals: 

This is not a good teaching website but would be good for double checking math

 

Implementation Notes: 

I used this to double check my Slater's rules calculations (and found a mistake in my answer key!)

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