Topic 25: Infrared Spectroscopy

25.1Why are IR absorptions generally quite broad?
 
25.2What sort of IR absorptions are extraordinarily broad? Why?
 
25.3What is wavenumber, and what are its units as used in IR spectroscopy?
 
25.4Does increasing wavenumber correspond to increasing or decreasing energy of absorption?
 
25.5What is the overall range in wavenumbers of a typical IR spectrum?
 
25.6What is the range in wavenumbers of the functional group region of an IR spectrum? Why is it called that?
 
25.7What is the range in wavenumbers of the fingerprint region of an IR spectrum? Why is it called that? Why do we generally not look for functional groups there?
 
25.8Why do C=C bonds vibrate at higher energy than C-C bonds?
 
25.9Why do C-H bonds vibrate at FAR higher energy than C-C bonds?
 
25.10What is reduced mass, and how does that play into the difference in vibrational energies of C-H and C-C bonds?
 
25.11How can we tell from an IR spectrum that a compound is probably an alcohol? a ketone? an aldehyde? a carboxylic acid? an ester? a primary amine? a secondary amine? an alkyne? a terminal alkyne? an aromatic comound?
 
25.12How can we use IR to see if our product in lab that we have recrystallized from water is dry and so also ready for us to take its melting point?
 
12 questions
364 questions for Organic I

364 Questions for Organic I

Dearest Student. This web page is a set of questions I call Detailed Intended Learning Outcomes For Organic Chemistry (Part I). Some time ago I asked myself, "Bob, what do you think are the key questions that you hope students will be able to answer after taking Chemistry 247 at St. Olaf College?" So here you have them. Some are very simple; some require more thought. All are good questions to be thinking about as you read, discuss, and master the practical aspects of organic chemistry. They are discussion starters and review tips. There are no answers here (though there are some clues). The questions are here to help you focus on what's important (to me, at least!) and organize your learning process. The questions are grouped into topics. Bite-size chunks. Take them a few at a time. Don't feast on them all at one sitting!

(preliminary version 2021.01.15 feeback: Bob Hanson)