Question 1

When the concentration of an analyte increases by a factor of three,what will happen to the UV-vis absorbance?

Accepted Answer

A) It will decrease by a factor of three. 
B) It will increase by a factor of one-third. 
C) It will increase by a factor of three. 
D) It will decrease by a factor one-third. 
E) It will increase by a factor of log(3). 
A) It will decrease by a factor of three. 
B) It will increase by a factor of one-third. 
C) It will increase by a factor of three. 
D) It will decrease by a factor one-third. 
E) It will increase by a factor of log(3). C

Question 2

Which of the following structural features is consistent with the spectrum shown below?

Accepted Answer

A) An unsubstituted benzene ring 
B) A monosubstituted benzene ring 
C) An ortho-substituted benzene ring 
D) A meta-substituted benzene ring 
E) A para-substituted benzene ring 
A) An unsubstituted benzene ring 
B) A monosubstituted benzene ring 
C) An ortho-substituted benzene ring 
D) A meta-substituted benzene ring 
E) A para-substituted benzene ring E

Question 3

Which of the following would you expect to have the lower-frequency C   
O stretch? Explain.

Accepted Answer

The carboxylate anion (B)would show a lower-frequency C   O stretch than the carboxylic acid (A).This is because it contains a significant resonance contributor in which the negative charge is localized on the other oxygen,as shown below.Therefore,the double bond in B is weaker (in fact,it is more accurately a bond with an order of 1.5 rather than a actual double bond),and a weaker bond corresponds to a lower frequency.

Question 4

Which structure is most consistent with the IR spectrum shown below?

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Question 5

Which of the following statements is false?

Accepted Answer

A) A photon's energy increases as its frequency increases. 
B) As a photon's wavelength increases, its frequency increases. 
C) As the energy of a photon decreases, its wavelength increases. 
D) The wavelength of a photon increases as its frequency decreases. 
E) A photon with the longest wavelength has the lowest energy. 
A) A photon's energy increases as its frequency increases. 
B) As a photon's wavelength increases, its frequency increases. 
C) As the energy of a photon decreases, its wavelength increases. 
D) The wavelength of a photon increases as its frequency decreases. 
E) A photon with the longest wavelength has the lowest energy.

Question 6

Which of the following would you expect to have the longer λmax? Explain.

Accepted Answer

Structure B would have the longer λ_max.This

Question 7

Which of the following structural features is most consistent with the spectrum shown below?

Accepted Answer

A) Secondary amide 
B) Ketone 
C) Primary amine 
D) Aldehyde 
E) Secondary alcohol 
A) Secondary amide 
B) Ketone 
C) Primary amine 
D) Aldehyde 
E) Secondary alcohol

Question 8

An unknown compound with the molecular formula C4H7N produces the IR spectrum shown below.What is the most likely identity of the unknown compound?

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Question 9

Which of the following would be likely to exhibit an absorption band of moderate to strong intensity at 2240 cmF1F1F1S1F1F1F101?

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Question 10

A sample has an absorbance of 0.68 at a particular wavelength in the UV-vis region.The intensity of the radiation source in the spectrophotometer was 1.5 × 10-4 W.What was the intensity of radiation measured by the detector?

Accepted Answer

Question 11

Which of the following would be expected to have the highest-intensity peak near 2950 cm-1?

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Question 12

Which of the electron transitions shown in the figure below would correspond to the UV-vis absorption band at the longest wavelength?

Accepted Answer

A) 1 
B) 2 
C) 3 
D) 4 
E) 5 
A) 1 
B) 2 
C) 3 
D) 4 
E) 5

Question 13

A UV-vis radiation source has an intensity of 1.0 × 10-3 W.The radiation is sent through an analyte,and the detector measures an intensity of 2.8 × 10-4 W.What is the absorbance of the sample?

Accepted Answer

A) 0.28 
B) 3.6 
C) 0.72 
D) 0.55 
E) 1.0 
A) 0.28 
B) 3.6 
C) 0.72 
D) 0.55 
E) 1.0

Question 14

Draw the symmetric N-H stretch that would occur in the molecule below.

Accepted Answer

The answer of Draw the symmetric N-H stretch that would...

Question 15

Calculate the approximate wavelength (in nm)required to excite the vibrational frequency indicated in the spectrum below.

Accepted Answer

The answer of Calculate the approximate wavelength (in nm)required to...

Question 16

Match each compound below to its IR spectrum based on the intensity of the alkane CF1F1F1S1F1F1F10H stretch absorption band.

Accepted Answer

Spectrum 1 = compound A (benze

Question 17

Which of the following bonds would have a higher stretching frequency? Explain.

Accepted Answer

Bond B would have a higher stretching fr

Question 18

If we wished to monitor a frequency to determine whether the reaction below had taken place,which frequency would be the best choice?

Accepted Answer

A) 2200 cm-1 
B) 1600 cm-1 
C) 3300 cm-1 
D) 1050 cm-1 
E) 2950 cm-1 
A) 2200 cm-1 
B) 1600 cm-1 
C) 3300 cm-1 
D) 1050 cm-1 
E) 2950 cm-1

Question 19

Rank the following bonds in order of increasing stretching vibration frequency.

Accepted Answer

The answer of Rank the following bonds in order of...

Question 20

Which of the following would not show any peaks at frequencies higher than 3000 cm-1 in its IR spectrum?

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Exam 17: Structure Determination 1: Ultravioletvisible and Infrared Spectroscopies

When the concentration of an analyte increases by a factor of three,what will happen to the UV-vis absorbance?

Which of the following structural features is consistent with the spectrum shown below?

Which of the following would you expect to have the lower-frequency C O stretch? Explain.

Which structure is most consistent with the IR spectrum shown below?

Which of the following statements is false?

Which of the following would you expect to have the longer λmax? Explain.

Which of the following structural features is most consistent with the spectrum shown below?

An unknown compound with the molecular formula C4H7N produces the IR spectrum shown below.What is the most likely identity of the unknown compound?

Which of the following would be likely to exhibit an absorption band of moderate to strong intensity at 2240 cm1?

A sample has an absorbance of 0.68 at a particular wavelength in the UV-vis region.The intensity of the radiation source in the spectrophotometer was 1.5 × 10-4 W.What was the intensity of radiation measured by the detector?

Which of the following would be expected to have the highest-intensity peak near 2950 cm-1?

Which of the electron transitions shown in the figure below would correspond to the UV-vis absorption band at the longest wavelength?

A UV-vis radiation source has an intensity of 1.0 × 10-3 W.The radiation is sent through an analyte,and the detector measures an intensity of 2.8 × 10-4 W.What is the absorbance of the sample?

Draw the symmetric N-H stretch that would occur in the molecule below.

Calculate the approximate wavelength (in nm)required to excite the vibrational frequency indicated in the spectrum below.

Match each compound below to its IR spectrum based on the intensity of the alkane CH stretch absorption band.

Which of the following bonds would have a higher stretching frequency? Explain.

If we wished to monitor a frequency to determine whether the reaction below had taken place,which frequency would be the best choice?

Rank the following bonds in order of increasing stretching vibration frequency.

Which of the following would not show any peaks at frequencies higher than 3000 cm-1 in its IR spectrum?

Atomic and Molecular Structure

Interchapter: Nomenclature 1-4

Interchapter 1molecular Orbital Theory and Chemical Reactions

Three-Dimensional Geometry,intermolecular Interactions,and Physical Properties

Orbital Interactions 1: Hybridization and Two-Center Molecular Orbitals

Isomerism 1: Conformational and Constitutional Isomers

Isomerism 2: Chirality,enantiomers,and Diastereomers

The Proton Transfer Reaction: an Introduction to Mechanisms,thermodynamics,and Charge Stability

An Overview of the Most Common Elementary Steps

An Introduction to Multistep Mechanisms: Sn1 and E1 Reactions

Nucleophilic Substitution and Elimination Reactions 1: Competition Among Sn2,sn1,e2,and E1 Reactions

Nucleophilic Substitution and Elimination Reactions 2: Reactions That Are Useful for Synthesis

Electrophilic Addition to Nonpolar Π Bonds 1: Addition of a Brønsted Acid

Electrophilic Addition to Nonpolar Π Bonds 2: Reactions Involving Cyclic Transition States

Organic Synthesis 1: Beginning Concepts

Orbital Interactions 2: Extended Π Systems,conjugation,and Aromaticity

Structure Determination 2: Nuclear Magnetic Resonance Spectroscopy and Mass Spectrometry

Nucleophilic Addition to Polar Π Bonds 1: Addition of Strong Nucleophiles

Nucleophilic Addition to Polar Π Bonds 2: Addition of Weak Nucleophiles and Acid and Base Catalysis

Organic Synthesis 2: Intermediate Topics in Synthesis Design,and Useful Reduction and Oxidation Reactions

Nucleophilic Additionelimination Reactions 1: the General Mechanism Involving Strong Nucleophiles

Nucleophilic Additionelimination Reactions 2: Weak Nucleophiles

Electrophilic Aromatic Substitution 1: Substitution on Benzene; Useful Accompanying Reactions

Electrophilic Aromatic Substitution 2: Substitution on Mono- and Disubstituted Benzene and Other Aromatic Rings

The Dielsalder Reaction and Other Pericyclic Reactions

Reactions Involving Free Radicals

Polymers

Filters

Which of the following would you expect to have the longer λ_max? Explain.

An unknown compound with the molecular formula C₄H₇N produces the IR spectrum shown below.What is the most likely identity of the unknown compound?

Which of the following would be likely to exhibit an absorption band of moderate to strong intensity at 2240 cm^¹?

A sample has an absorbance of 0.68 at a particular wavelength in the UV-vis region.The intensity of the radiation source in the spectrophotometer was 1.5 × 10^-4 W.What was the intensity of radiation measured by the detector?

Which of the following would be expected to have the highest-intensity peak near 2950 cm^-1?

A UV-vis radiation source has an intensity of 1.0 × 10^-3 W.The radiation is sent through an analyte,and the detector measures an intensity of 2.8 × 10^-4 W.What is the absorbance of the sample?

Which of the following would not show any peaks at frequencies higher than 3000 cm^-1 in its IR spectrum?