Organic Chem 2 Quiz 2

Topics: Infrared, Infrared spectroscopy, Wavelength Pages: 6 (610 words) Published: January 24, 2015
Study Guide: Exam 1
1.What type(s) of molecular motion is (are) observed using infrared spectroscopy?   
A.Stretching and bending
B.Rotation and excitation
C.Spin flipping
D.Fragmentation
 
2.The functional group region of an infrared spectrum is 
 
A.where the cations appear.
B.>1500 cm-1.
C.2500 cm-1.
 
3.Stronger bonds will be found where in the infrared spectrum?   
A.Higher molecular weight
B.Lower molecular weight
C.Lower wavenumbers
D.Higher wavenumbers
 
4.Compared to a C-H bond, a C-D bond will vibrate where in the infrared spectrum?   
A.Higher molecular weight
B.Lower molecular weight
C.Lower wavenumbers
D.Higher wavenumbers
 
5.Why does an alkyne carbon-carbon bond vibrate at a higher wavenumber than an alkene carbon-carbon bond?   
A.It is stronger.
B.It is weaker.
C.It has fewer hydrogens.
D.It makes a less stable cation.
 
6.Why is the infrared absorption for the stretching motion of internal alkynes rarely observed?   
A.They do not form cations.
B.They are too strong.
C.There must be a change in dipole.
D.They don't have hydrogens.
 
7.Consider the three organic compounds drawn below. Which of the following statements is (are) true about the IR spectra of compounds A, B, and C?

   
 
A.Compound A shows strong absorptions at 3000 cm-1 and 1700 cm-1. B.Compound B shows strong absorptions at 3000 cm-1 and 2250 cm-1. C.Compound C shows strong absorptions at 3000 cm-1 and 3200-3600 cm-1. D.Statements (Compound A shows strong absorptions at 3000 cm-1 and 1700 cm-1) and (Compound C shows strong absorptions at 300 cm-1 and 3200-3600 cm-1) are true. E.Statements (Compound A shows strong absorptions at 3000 cm-1 and 1700 cm-1), (Compound B shows strong absorptions at 3000 cm-1 and 2250 cm-1), and (Compound C shows strong absorptions at 3000 cm-1 and 3200-3600 cm-1) are all true.  

8.In an IR spectrum, which of the circled C-H bonds exhibits a stretching absorption at the highest wave number?

   
 
A.A
B.B
C.C
 
9.Which of the following statements is (are) accurate about the IR spectrum of compounds A, B, and C below?    
 
A.Compound A shows absorptions at 3000 and 1700 cm-1.
B.Compound B show absorptions at 3200-3600 and 1650 cm-1.
C.Compound C show absorptions at 3200-3600 and 3000 cm-1.
D.Both (Compound A shows absorptions at 3000 and 1700 cm-1) and (Compound B show absorptions at 3200-3600 and 1650 cm-1) are true. E.Statements (Compound A shows absorptions at 3000 and 1700 cm-1), (Compound B show absorptions at 3200-3600 and 1650 cm-1), and (Compound C show absorptions at 3200-3600 and 3000 cm-1) are all true.  

9.Which of the circled C-H bonds absorbs at the highest wave number in the IR spectrum?

   
 
A.A
B.B
C.C
D.D
E.E
 
10.Which of the following statements is (are) true about the IR spectrum of the compound drawn below?

   
 
A.It shows absorptions at 3000-3150 cm-1 and 1720 cm-1.
B.It shows absorptions at 3000-2850 cm-1 and 2150 cm-1.
C.It shows absorptions at 2150 cm-1 and 1650 cm-1.
D.It shows absorptions at 2150 cm-1 and 1720 cm-1.
E.Both statements (It shows absorptions at 3000-2850 cm-1 and 2150 cm-1) and (It shows absorptions at 2150 cm-1 and 1720 cm-1) are true.  
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