magnetism by Evans method

Submitted by Adam Johnson / Harvey Mudd College on Tue, 05/31/2016 - 16:27
Description

After I teach my students about magnetism and magnetic properties in coordination compounds, I spend a day showing how the data is collected and analyzed. I teach them about the Gouy balance, the Evans method of determining magnetism by NMR, and SQUID magnetometry. I also show them real data that I collected as an undergraduate or graduate student, and have them interpret and analyze it.

The only experiment that we can do locally is the Evans method, so I spend more time on this technique. We use the method during the metal acac laboratory.

Water reclamation on the ISS: “Houston, we have a problem.”

Submitted by Adam Johnson / Harvey Mudd College on Sun, 05/15/2016 - 13:57
Description

Equilibrium reactions are those that are dynamic: the reaction can shift to form more reactants or more products depending on the physical or chemical conditions present. They were discovered and described empirically, but have a thermodynamic basis in the Gibbs Energy of the reaction. A reaction at equilibrium has both reactants and products present, and the rate of formation of products is equal to the rate of formation of reactants. A common application of equilibrium is the chemistry of aqueous acids. Acid strength is measured by the pH scale.

soapmaking activity

Submitted by Adam Johnson / Harvey Mudd College on Sat, 05/14/2016 - 22:36
Description

This in-class activity is designed to follow the linked lecture/demonstration on soapmaking. The soaps cure enough to be handled in 48 hours if kept warm, and the students can feel the difference in the canola/coconut oil soaps.

The calcuations go through the major reactions, functional groups, and physical properties of soap molecules, and ends with the calculation of molecular weight for a mixture of substances. This could be related to a later polymer unit.

soapmaking lecture/demo

Submitted by Adam Johnson / Harvey Mudd College on Sat, 05/14/2016 - 22:26
Description

This is a short presentation that outlines the major chemical reactions of soapmaking. Included are instructions for making two soaps, one from canola oil, the other from coconut oil. These two soaps have very different hardnesses, which can be explained by examining the structures of the oils. If you have never made soap before, it isn't that difficult, but it does use concentrated NaOH so is very caustic before the reaction is done. The linked websited have good instructions for soapmaking as well.

Crystal Field Theory and Gems--Guided Inquiry

Submitted by Adam Johnson / Harvey Mudd College on Sat, 05/14/2016 - 21:42
Description

The colors of transition metal compounds are highly variable. Aqueous solutions of nickel are green, of copper are blue, and of vanadium can range from yellow to blue to green to violet. What is the origin of these colors? A simple geometrical model known as crystal field theory can be used to differentiate the 5 d orbitals in energy. When an electron in a low-lying orbital interacts with visible light, the electron can be promoted to a higher-lying orbital with the absorption of a photon. Our brains perceive this as color.

Ligand Field Correlations for Square Pyramidal Oxovanadium(III)

Submitted by Matt Whited / Carleton College on Fri, 04/22/2016 - 10:37
Description

Students work in groups to derive the ligand-field diagram for a square-pyramidal vanadium(III) oxo complex using octahedral V(III) as a starting point. The activity helps students to correlate changes in orbital energies as a function of changing ligands and geometry as well as rationalizing why certain geometries can be particularly good (or bad) for particular complexes. The activity also helps students see why oxo complexes of early metals are frequently best described as triple bonds.

Build-Your-Own Molecular Orbitals

Submitted by Anne Bentley / Lewis & Clark College on Fri, 02/19/2016 - 12:44
Description

This is a truly hands-on activity in which students manipulate paper cutouts of carbon atomic orbitals and oxygen group orbitals to identify combinations with identical symmetry and build the carbon dioxide molecular orbital diagram. The activity pairs well with the treatment of MO theory in Miessler, Fischer, and Tarr, Chapter 5. An optional computational modeling component can be added at the end.

Point Group Battles Activity

Submitted by Darren Achey / Kutztown University on Thu, 10/15/2015 - 11:48
Description

In this activity, a pair of students are show an object or molecule and are asked to determine the point group before their competitor.

Annotated List of Metal-Containing Structures in the Cambridge Structural Database Teaching Subset

Submitted by Anthony L. Fernandez / Merrimack College on Sat, 08/15/2015 - 00:46
Description

The Cambridge Crystallographic Data Centre (CCDC) provides many free programs that can be used to view and manipulate crystal structures. Additionally, they have made a subset of the Cambridge Structural Database (CSD) available for teaching purposes and many educational activities have been created to go along with this teaching subset (see link below). This teaching subset can be freely viewed through the WebCSD interface or can be used in the freely-available Mercury program. (Mercury is avaliable for Mac, Windows, and Linux systems.)