Question 1

Why is the infrared absorption for the stretching motion of internal alkynes rarely observed?

Accepted Answer

A) They do not form cations. 
B) They are too strong. 
C) Stretching in internal alkynes does not involve a change in dipole moment. 
D) They do not have hydrogens. 
A) They do not form cations. 
B) They are too strong. 
C) Stretching in internal alkynes does not involve a change in dipole moment. 
D) They do not have hydrogens.

Question 2

13C NMR is a technique in which the total number of signals represents the number of unique carbon atoms in a molecule.Propose a structure that is consistent with the following data. a.The IR includes peaks at 1603 and 1495 cm-1.
b.The 13C NMR has a total of 7 signals.
c.The compound has one acidic proton.

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
A) I 
B) II 
C) III 
D) IV

Question 3

Examine the IR below and classify the compound.

Accepted Answer

A) Alcohol 
B) Aldehyde 
C) Carboxylic acid 
D) Ketone 
A) Alcohol 
B) Aldehyde 
C) Carboxylic acid 
D) Ketone

Question 4

An IR spectrum has the following potentially important absorptions: 3091,3067,2963,2921,2252,1603,1499,1455,1416,1078,1031,941,735,and 696 cm-1.Indicate which structure corresponds to the IR data.

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
A) I 
B) II 
C) III 
D) IV

Question 5

Examine the IR below and classify the compound.

Accepted Answer

A) Alcohol 
B) Arene 
C) Amine 
D) Ketone 
E) Carbocylic acid 
A) Alcohol 
B) Arene 
C) Amine 
D) Ketone 
E) Carbocylic acid

Question 6

Which of the indicated C-H bonds absorbs at the lowest wave number in the IR spectrum?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
A) I 
B) II 
C) III 
D) IV

Question 7

Consider the three organic compounds drawn below.Which of the following statements is (are)true about the IR spectra of I,II,and III?

Accepted Answer

A) I shows strong absorptions at 2950 cm-1 and 1700 cm-1. 
B) II shows strong absorptions at 2950 cm-1 and 2250 cm-1. 
C) III shows strong absorptions at 2950 cm-1 and 3200-3600 cm-1. 
D) Statements (I shows strong absorptions at 2950 cm-1 and 1700 cm-1)and (III shows strong absorptions at 2950 cm-1 and 3200-3600 cm-1)are true. 
A) I shows strong absorptions at 2950 cm-1 and 1700 cm-1. 
B) II shows strong absorptions at 2950 cm-1 and 2250 cm-1. 
C) III shows strong absorptions at 2950 cm-1 and 3200-3600 cm-1. 
D) Statements (I shows strong absorptions at 2950 cm-1 and 1700 cm-1)and (III shows strong absorptions at 2950 cm-1 and 3200-3600 cm-1)are true.

Question 8

Ignoring sp3 CH stretching,estimate where the major peak be in the following compound's IR.

Accepted Answer

A) 3300 cm-1 
B) 3100 cm-1 
C) 2250 cm-1 
D) 1750 cm-1 
A) 3300 cm-1 
B) 3100 cm-1 
C) 2250 cm-1 
D) 1750 cm-1

Question 9

Which of the following structures is consistent with a compound that displays a molecular ion peak at 56 and infrared signals at 2250 and 3600-3200 cm-1?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
A) I 
B) II 
C) III 
D) IV

Question 10

Which of the following information is primarily obtained from an IR spectrum?

Accepted Answer

A) Conjugated p system present in a compound. 
B) Functional groups present in a compound. 
C) Molecular weight of a compound. 
D) The carbon and hydrogen framework of a compound. 
A) Conjugated p system present in a compound. 
B) Functional groups present in a compound. 
C) Molecular weight of a compound. 
D) The carbon and hydrogen framework of a compound.

Question 11

What type(s)of molecular motion is (are)observed using infrared spectroscopy?

Accepted Answer

A) Stretching and bending 
B) Rotation and excitation 
C) Spin flipping 
D) Fragmentation 
A) Stretching and bending 
B) Rotation and excitation 
C) Spin flipping 
D) Fragmentation

Question 12

Ignoring sp3 CH stretching,estimate where the major peak be in the following compound's IR.

Accepted Answer

A) 3300 cm-1 
B) 3100 cm-1 
C) 2250 cm-1 
D) 1750 cm-1 
A) 3300 cm-1 
B) 3100 cm-1 
C) 2250 cm-1 
D) 1750 cm-1

Question 13

What type of signal(s)would you observe in the mass and/or infrared spectrum of the following compound?

Accepted Answer

A) A signal at 96 amu 
B) Two signals at 112 and 114 amu 
C) A signal at 1600 cm-1 
D) A signal at 1720 cm-1 
A) A signal at 96 amu 
B) Two signals at 112 and 114 amu 
C) A signal at 1600 cm-1 
D) A signal at 1720 cm-1

Question 14

You are given a bottle of an organic liquid and told it must be either cyclohexane or 1-hexene.Which of the following statements is (are)true about these two compounds?

Accepted Answer

A) The two compounds can be differentiated by their mass spectra because they will have molecular ion peaks at different m/z. 
B) 1-Hexene will show an absorption at 1650 cm-1 but cyclohexane will not. 
C) Both cyclohexane and 1-hexene will show C-H absorptions at about 2950 cm-1. 
D) Statements (1-Hexene will show an absorption at 1650 cm-1 but cyclohexane will not)and (Both cyclohexane and 1-hexene will show C-H absorptions at about 2950 cm-1)are both true. 
E) Statements (The two compounds can be differentiated by their mass spectra because they will have molecular ions at different masses),(1-Hexene will show an absorption at 1650 cm-1 but cyclohexane will not),and (Both cyclohexane and 1- hexene will show C-H absorptions at about 2950 cm-1)are all true. 
A) The two compounds can be differentiated by their mass spectra because they will have molecular ion peaks at different m/z. 
B) 1-Hexene will show an absorption at 1650 cm-1 but cyclohexane will not. 
C) Both cyclohexane and 1-hexene will show C-H absorptions at about 2950 cm-1. 
D) Statements (1-Hexene will show an absorption at 1650 cm-1 but cyclohexane will not)and (Both cyclohexane and 1-hexene will show C-H absorptions at about 2950 cm-1)are both true. 
E) Statements (The two compounds can be differentiated by their mass spectra because they will have molecular ions at different masses),(1-Hexene will show an absorption at 1650 cm-1 but cyclohexane will not),and (Both cyclohexane and 1- hexene will show C-H absorptions at about 2950 cm-1)are all true.

Question 15

Which of the following statements is (are)true about a compound that has molecular ion peaks in its mass spectrum at mass 170 and 172 and shows prominent peaks in its IR spectrum at 3150-3000 and 1600 cm-1?

Accepted Answer

A) The compound is not pure. 
B) The compound contains a halogen. 
C) The compound contains an OH group and Csp3-H hybridized bonds. 
D) Both (The compound is not pure)and (The compound contains a halogen)are true statements. 
E) Both (The compound is not pure)and (The compound contains an OH group and Csp3-H hybridized bonds)are true statements. 
A) The compound is not pure. 
B) The compound contains a halogen. 
C) The compound contains an OH group and Csp3-H hybridized bonds. 
D) Both (The compound is not pure)and (The compound contains a halogen)are true statements. 
E) Both (The compound is not pure)and (The compound contains an OH group and Csp3-H hybridized bonds)are true statements.

Question 16

Which of the following compounds will have the lowest wavenumber for carbonyl absorption?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
A) I 
B) II 
C) III 
D) IV

Question 17

Which of the following statements is (are)true about a compound that has a molecular ion peak in its mass spectrum at mass 104 and shows prominent peaks in its IR spectrum at 3200-2850 cm-1?

Accepted Answer

A) The compound has a molecular mass of 104. 
B) The compound contains a C=O group and Csp3-H hybridized bonds. 
C) The compound contains an OH group and Csp3-H hybridized bonds. 
D) Both (The compound has a molecular mass of 104)and (The compound contains a C=O group and Csp3-H hybridized bonds)are true statements. 
E) Both (The compound has a molecular mass of 104)and (The compound contains an OH group and Csp3-H hybridized bonds)are true statements. 
A) The compound has a molecular mass of 104. 
B) The compound contains a C=O group and Csp3-H hybridized bonds. 
C) The compound contains an OH group and Csp3-H hybridized bonds. 
D) Both (The compound has a molecular mass of 104)and (The compound contains a C=O group and Csp3-H hybridized bonds)are true statements. 
E) Both (The compound has a molecular mass of 104)and (The compound contains an OH group and Csp3-H hybridized bonds)are true statements.

Question 18

Which of the following statements is (are)accurate about the IR spectrum of compounds I,II,and III below?

Accepted Answer

A) Compound I shows absorptions at 2950 and 1700 cm-1. 
B) Compound II shows absorptions at 3200-3600 and 1650 cm-1. 
C) Compound III shows absorptions at 3200-3600 and 2950 cm-1. 
D) Both (Compound I shows absorptions at 2950 and 1700 cm-1)and (Compound II shows absorptions at 3200-3600 and 1650 cm-1)are true. 
A) Compound I shows absorptions at 2950 and 1700 cm-1. 
B) Compound II shows absorptions at 3200-3600 and 1650 cm-1. 
C) Compound III shows absorptions at 3200-3600 and 2950 cm-1. 
D) Both (Compound I shows absorptions at 2950 and 1700 cm-1)and (Compound II shows absorptions at 3200-3600 and 1650 cm-1)are true.

Question 19

Compared to a C-H bond,a C-D bond will vibrate where in the infrared spectrum?

Accepted Answer

A) Higher molecular weight 
B) Lower molecular weight 
C) Lower wavenumbers 
D) Higher wavenumbers 
A) Higher molecular weight 
B) Lower molecular weight 
C) Lower wavenumbers 
D) Higher wavenumbers

Exam 31: Spectroscopy B: Infrared Spectroscopy

Why is the infrared absorption for the stretching motion of internal alkynes rarely observed?

Examine the IR below and classify the compound.

An IR spectrum has the following potentially important absorptions: 3091,3067,2963,2921,2252,1603,1499,1455,1416,1078,1031,941,735,and 696 cm-1.Indicate which structure corresponds to the IR data.

Examine the IR below and classify the compound.

Which of the indicated C-H bonds absorbs at the lowest wave number in the IR spectrum?

Consider the three organic compounds drawn below.Which of the following statements is (are)true about the IR spectra of I,II,and III?

Ignoring sp3 CH stretching,estimate where the major peak be in the following compound's IR.

Which of the following structures is consistent with a compound that displays a molecular ion peak at 56 and infrared signals at 2250 and 3600-3200 cm-1?

Which of the following information is primarily obtained from an IR spectrum?

What type(s)of molecular motion is (are)observed using infrared spectroscopy?

Ignoring sp3 CH stretching,estimate where the major peak be in the following compound's IR.

What type of signal(s)would you observe in the mass and/or infrared spectrum of the following compound?

You are given a bottle of an organic liquid and told it must be either cyclohexane or 1-hexene.Which of the following statements is (are)true about these two compounds?

Which of the following statements is (are)true about a compound that has molecular ion peaks in its mass spectrum at mass 170 and 172 and shows prominent peaks in its IR spectrum at 3150-3000 and 1600 cm-1?

Which of the following compounds will have the lowest wavenumber for carbonyl absorption?

Which of the following statements is (are)true about a compound that has a molecular ion peak in its mass spectrum at mass 104 and shows prominent peaks in its IR spectrum at 3200-2850 cm-1?

Which of the following statements is (are)accurate about the IR spectrum of compounds I,II,and III below?

Compared to a C-H bond,a C-D bond will vibrate where in the infrared spectrum?

Structure and Bonding

Acids and Bases

Introduction to Organic Molecules and Functional Groups

Alkanes

Stereochemistry

Understanding Organic Reactions

Alkyl Halides and Nucleophilic Substitution

Alkyl Halides and Elimination Reactions

Alcohols,ethers,and Related Compounds

Alkenes and Addition Reactions

Alkynes and Synthesis

Oxidation and Reduction

Radical Reactions

Conjugation,resonance,and Dienes

Benzene and Aromatic Compounds

Reactions of Aromatic Compounds

Introduction to Carbonyl Chemistry; Organometallic Reagents; Oxidation and Reduction

Aldehydes and Ketones - Nucleophilic Addition

Carboxylic Acids and the Acidity of the O-H Bond

Carboxylic Acids and Their Derivatives Nucleophilic Acyl Substitution

Substitution Reactions of Carbonyl Compounds at the a Carbon

Carbonyl Condensation Reactions

Amines

Carbon-Carbon Bond-Forming Reactions in Organic Synthesis

Pericyclic Reactions

Carbohydrates

Amino Acids and Proteins

Synthetic Polymers

Lipids

Spectroscopy A: Mass Spectrometry

Spectroscopy C: Nuclear Magnetic Resonance Spectroscopy

Filters

An IR spectrum has the following potentially important absorptions: 3091,3067,2963,2921,2252,1603,1499,1455,1416,1078,1031,941,735,and 696 cm^-1.Indicate which structure corresponds to the IR data.

Ignoring sp³ CH stretching,estimate where the major peak be in the following compound's IR.

Which of the following structures is consistent with a compound that displays a molecular ion peak at 56 and infrared signals at 2250 and 3600-3200 cm^-1?

Ignoring sp³ CH stretching,estimate where the major peak be in the following compound's IR.

Which of the following statements is (are)true about a compound that has molecular ion peaks in its mass spectrum at mass 170 and 172 and shows prominent peaks in its IR spectrum at 3150-3000 and 1600 cm^-1?

Which of the following statements is (are)true about a compound that has a molecular ion peak in its mass spectrum at mass 104 and shows prominent peaks in its IR spectrum at 3200-2850 cm^-1?