Question 1

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.E) A) and D)
F) A) and B) A

Question 2

Examine the IR below and classify the compound.

Accepted Answer

A)   Alcohol
B)   Aldehyde
C)   Amine
D)   Ketone
E)   Carboxylic acidF) A) and D)
G) All of the above

Question 3

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 wavenumbersE) C) and D)
F) All of the above

Question 4

Examine the IR below and classify the compound.

Accepted Answer

A)   Alcohol
B)   Aldehyde
C)   Carboxylic acid
D)   KetoneE) None of the above
F) All of the above C

Question 5

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? -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." class="answers-bank-image d-inline" rel="preload" >

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.F) None of the above
G) A) and B)

Question 6

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? -1?   A)  I B)  II C)  III D)  IV" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   I
B)   II
C)   III
D)   IVE) A) and C)
F) A) and B)

Question 7

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.E) None of the above
F) All of the above

Question 8

Which of the following structures is consistent with a compound that displays a molecular ion peak at 103 and infrared signals at 2250 and 1600 cm-1? -1?   A)  I B)  II C)  III D)  IV" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   I
B)   II
C)   III
D)   IVE) A) and B)
F) A) and D)

Question 9

What type of signal(s)  would you observe in the mass and (or)  infrared spectrum of the following compound? -1 B)  A signal at 3300 cm-1 C)  A single mass peak at 92 amu D)  Two mass peaks at 92 and 94 amu" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   A signal at 1600 cm-1
B)   A signal at 3300 cm-1
C)   A single mass peak at 92 amu
D)   Two mass peaks at 92 and 94 amuE) None of the above
F) C) and D)

Question 10

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.F) B) and E)
G) C) and D)

Question 11

Which of the following statements is (are)  accurate about the IR spectrum of compounds I, II, and III below? -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." class="answers-bank-image d-inline" rel="preload" >

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.E) A) and D)
F) None of the above

Question 12

You observe a compound that exhibits a mass spectrum with peak at 160 and a peak at 162, both of equal intensity. This compound contains:

Accepted Answer

A)   Two chlorine atoms
B)   One iodine atom
C)   One bromine atom
D)   Two bromine atomsE) None of the above
F) A) and B) C

Question 13

A compound X has a molecular ion peak in its mass spectrum at m/z 136. What information does this tell us about X?

Accepted Answer

A)   X has a molecular mass of 136.
B)   The molecular formula for X is C8H8O2.
C)   The empirical formula for X is C4H4O.
D)   Both A (X has a molecular mass of 136)  and B (The molecular formula for X is C8H8O2)  are true.
E)   Statements (X has a molecular mass of 136) , (The molecular formula for X is C8H8O2) , and (The empirical formula for X is C4H4O)  are all true.F) A) and D)
G) All of the above

Question 14

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-1E) All of the above
F) A) and C)

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 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.F) B) and E)
G) B) and C)

Question 16

Consider the three organic compounds drawn below. Which of the following statements is (are)  true about the IR spectra of I, II, and III? -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." class="answers-bank-image d-inline" rel="preload" >

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.E) B) and D)
F) B) and C)

Question 17

In an IR spectrum, which of the indicated C-H bonds exhibits a stretching absorption at the largest wave number?

Accepted Answer

A)   I
B)   II
C)   III
D)   IVE) B) and C)
F) A) and D)

Question 18

The base peak in a mass spectrum corresponds to the most stable fragment. Propose a structure for a compound that is consistent with the following data. 
(a)  The molecular ion peak has m/z = 116
(b)  The base peak is at m/z = 59.
(c)  The compound is composed of C, H and O atoms.
(d)  The IR spectrum shows a strong absorbance at 3257 cm-1. -1.   A)  I B)  II C)  III D)  IV" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   I
B)   II
C)   III
D)   IVE) A) and B)
F) A) and C)

Question 19

Which of the following structures is consistent with a compound that displays a molecular ion peak at 84 and infrared signals at 3000-2850 cm-1 and no signals between 3000-3300 cm-1? -1 and no signals between 3000-3300 cm-1?   A)  I B)  II C)  III D)  IV" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   I
B)   II
C)   III
D)   IVE) All of the above
F) B) and C)

Question 20

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

Accepted Answer

A)   Conjugated  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.E) A) and C)
F) C) and D)

Exam 13: Mass Spectrometry and Infrared Spectroscopy

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

Correct Answer
verified
A

Examine the IR below and classify the compound.

Correct Answer
verified

Stronger bonds will be found where in the infrared spectrum?

Correct Answer
verified

Examine the IR below and classify the compound.

Correct Answer
verified
C

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?

Correct Answer
verified

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?

Correct Answer
verified

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

Correct Answer
verified

Which of the following structures is consistent with a compound that displays a molecular ion peak at 103 and infrared signals at 2250 and 1600 cm^-1?

Correct Answer
verified

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

Correct Answer
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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?

Correct Answer
verified

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

Correct Answer
verified

You observe a compound that exhibits a mass spectrum with peak at 160 and a peak at 162, both of equal intensity. This compound contains:

Correct Answer
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C

A compound X has a molecular ion peak in its mass spectrum at m/z 136. What information does this tell us about X?

Correct Answer
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The functional group region of an infrared spectrum is:

Correct Answer
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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?

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

Correct Answer
verified

In an IR spectrum, which of the indicated C-H bonds exhibits a stretching absorption at the largest wave number?

Correct Answer
verified

Correct Answer
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Which of the following structures is consistent with a compound that displays a molecular ion peak at 84 and infrared signals at 3000-2850 cm^-1 and no signals between 3000-3300 cm^-1?

Correct Answer
verified

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

Correct Answer
verified

Exam 13: Mass Spectrometry and Infrared Spectroscopy

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

Correct AnswerverifiedA

Examine the IR below and classify the compound.

Correct AnswerverifiedShow Answer

Stronger bonds will be found where in the infrared spectrum?

Correct AnswerverifiedShow Answer

Examine the IR below and classify the compound.

Correct AnswerverifiedC

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?

Correct AnswerverifiedShow Answer

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?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Which of the following structures is consistent with a compound that displays a molecular ion peak at 103 and infrared signals at 2250 and 1600 cm-1?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

You observe a compound that exhibits a mass spectrum with peak at 160 and a peak at 162, both of equal intensity. This compound contains:

Correct AnswerverifiedC

A compound X has a molecular ion peak in its mass spectrum at m/z 136. What information does this tell us about X?

Correct AnswerverifiedShow Answer

The functional group region of an infrared spectrum is:

Correct AnswerverifiedShow Answer

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?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

In an IR spectrum, which of the indicated C-H bonds exhibits a stretching absorption at the largest wave number?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Which of the following structures is consistent with a compound that displays a molecular ion peak at 84 and infrared signals at 3000-2850 cm-1 and no signals between 3000-3300 cm-1?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Correct Answer
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A

Correct Answer
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Correct Answer
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Correct Answer
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C

Correct Answer
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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?

Correct Answer
verified

Correct Answer
verified

Which of the following structures is consistent with a compound that displays a molecular ion peak at 103 and infrared signals at 2250 and 1600 cm^-1?

Correct Answer
verified

Correct Answer
verified

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?

Correct Answer
verified

Correct Answer
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Correct Answer
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C

Correct Answer
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Correct Answer
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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?

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Which of the following structures is consistent with a compound that displays a molecular ion peak at 84 and infrared signals at 3000-2850 cm^-1 and no signals between 3000-3300 cm^-1?

Correct Answer
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Correct Answer
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