Question 1

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 2

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 95 amu 
B) A signal at 94 amu 
C) Two signals at 95 and 94 amu 
D) A signal at 3600-3200 cm-1 
A) A signal at 95 amu 
B) A signal at 94 amu 
C) Two signals at 95 and 94 amu 
D) A signal at 3600-3200 cm-1

Question 3

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

Question 4

Examine the IR below and classify the compound.

Accepted Answer

A) Alkane 
B) Carboxylic acid 
C) Alcohol 
D) Alkene 
A) Alkane 
B) Carboxylic acid 
C) Alcohol 
D) Alkene

Question 5

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 6

An alkyne C-H bond absorbs at higher wave number than an alkene C-H bond.What does this tell you about the strength of these two bonds?

Accepted Answer

A) The alkene C-H bond is stronger. 
B) The alkyne C-H bond is stronger. 
C) The alkene C-C bond is stronger. 
D) The alkyne C-C bond is stronger. 
A) The alkene C-H bond is stronger. 
B) The alkyne C-H bond is stronger. 
C) The alkene C-C bond is stronger. 
D) The alkyne C-C bond is stronger.

Question 7

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

Question 8

Which of the following statements is (are) true about the IR spectrum of the compound drawn below?

Accepted Answer

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 2250 cm-1 and 1650 cm-1. 
D) It shows absorptions at 2250 cm-1 and 1720 cm-1. 
E) Both statements B (It shows absorptions at 3000-2850 cm-1 and 2250 cm-1) and D (It shows absorptions at 2250 cm-1 and 1720 cm-1) are true. 
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 2250 cm-1 and 1650 cm-1. 
D) It shows absorptions at 2250 cm-1 and 1720 cm-1. 
E) Both statements B (It shows absorptions at 3000-2850 cm-1 and 2250 cm-1) and D (It shows absorptions at 2250 cm-1 and 1720 cm-1) are true.

Question 9

The functional group region of an infrared spectrum is:

Accepted Answer

A) Where the cations appear 
B) Greater than or equal to 1500 cm-1 
C) Less than 1500 cm-1 
D) Greater than or equal to 2500 cm-1 
A) Where the cations appear 
B) Greater than or equal to 1500 cm-1 
C) Less than 1500 cm-1 
D) Greater than or equal to 2500 cm-1

Question 10

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 11

Stronger bonds will be found 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

Question 12

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 13

Why does an alkyne carbon-carbon triple bond vibrate at a higher wavenumber than an alkene carbon-carbon double bond?

Accepted Answer

A) It is stronger. 
B) It is weaker. 
C) It has fewer hydrogens. 
D) It makes a less stable cation. 
A) It is stronger. 
B) It is weaker. 
C) It has fewer hydrogens. 
D) It makes a less stable cation.

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

Examine the IR below and classify the compound.

Accepted Answer

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

Exam 13: Mass Spectrometry and Infrared Spectroscopy

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

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

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?

Examine the IR below and classify the compound.

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

An alkyne C-H bond absorbs at higher wave number than an alkene C-H bond.What does this tell you about the strength of these two bonds?

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

Which of the following statements is (are) true about the IR spectrum of the compound drawn below?

The functional group region of an infrared spectrum is:

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

Stronger bonds will be found where in the infrared spectrum?

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?

Why does an alkyne carbon-carbon triple bond vibrate at a higher wavenumber than an alkene carbon-carbon double bond?

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?

Examine the IR below and classify the compound.

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

Alkynes

Oxidation and Reduction

Nuclear Magnetic Resonance Spectroscopy

Radical Reactions

Conjugation, Resonance, and Dienes

Benzene and Aromatic Compounds

Reactions of Aromatic Compounds

Carboxylic Acids and the Acidity of the O-H Bond

Introduction to Carbonyl Chemistry;

Aldehydes and Ketones Nucleophilic Addition

Carboxylic Acids and Derivatives

Substitution Reactions of Carbonyl Compounds at the Alpha-Carbon

Carbonyl Condensation Reactions

Amines

Carbon-Carbon Bond Forming Reactions in Organic Synthesis

Pericyclic Reactions

Carbohydrates

Amino Acids and Proteins

Synthetic Polymers

Lipids

Filters

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?