Submitted by Nancy Williams / Scripps College, Pitzer College, Claremont McKenna College on Thu, 03/06/2008 - 12:31
My Notes
Categories
Prerequisites
No Prerequisites
Corequisites
General Chemistry
Course Level
First year
Topics Covered
Descriptive chemistry
Thermodynamics
Subdiscipline
Professional Practices, Skills, and Resources
Description

This is just a little worksheet that I use in a General Chemistry course to teach Gibbs Free Energy calculations and the idea of a coupled reaction, while foreshadowing ideas from metallurgy and electrochemistry (sacrificial reductants, entropy-driven smelting, fuels as reductants) for the end of the course when I generally address these.

Attachment Size
SmeltingwithThag.doc 210.5 KB
Equipment needs

Pens and/or pencils

Implementation Notes

At this point, I have generally discussed Gibbs Free Energy and explained how to calculate Gibbs Free Energy, Enthalpy, and Entropy of Reactions by using tabulated values for absolute entropies and Heats and Free Energies of Formation. This gives them a little practice at it, and shows some of the pitfalls (you can only use Delta Gf when you're at 25C, if your enthalpy is negative and entropy positive, there is no temperature at which the reaction becomes non-spontaneous, etc.)

Time Required
ca. 25 min, depending on the amount of attendant discussion

Evaluation

Evaluation Methods

None (yet)

Evaluation Results

They often forget to use coefficients in their calculations, for which this is a good reminder.

Creative Commons License
Attribution, Non-Commercial, Share Alike CC BY-NC-SA
Dr. J. Metzker / Georgia College
I believe there is a typo in the document.  Shouldn't the deltaH for Carbon (s) be 0 kJ/mol?
Tue, 07/26/2011 - 16:24 Permalink
Adam Johnson / Harvey Mudd College
The ∆H(s) for diamond is 0 kJ/mol.... if my dim memory of pchem serves me...
Tue, 07/26/2011 - 21:04 Permalink
Nancy Williams / Scripps College, Pitzer College, Claremont McKenna College
Right you are, Julia! That was inadvertantly copy-pasted from the CuO value on the previous page. The doc is now corrected. Thanks for the good eye!
Mon, 08/01/2011 - 01:32 Permalink