6th Edition Test Bank Docx Spectroscopy A Mass Spectrometry

Organic Chemistry, 6e (Smith)

Spectroscopy A Mass Spectrometry

1) In electron impact mass spectrometry (EIMS), what is being detected?

A) The molecular mass of the compound

B) The molecular formula of the compound

C) The mass to charge ratio of any ionic species

D) The mass to charge ratio of any neutral species

2) What type of feature will be observed in the EI mass spectrum of chlorobenzene?

A) An absorption at 3100 cm–1

B) A signal at 113

C) A signal at 112 and a signal at 114 in a ratio of 3:1

D) A signal at 112 and a signal at 114 in a ratio of 1:1

3) 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

A) two chlorine atoms.

B) one iodine atom.

C) one bromine atom.

D) two bromine atoms.

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

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.

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

A) A signal at 95 amu

B) A signal at 94 amu

C) Two signals at 95 and 94 amu

D) A signal at 106 amu

6) In a typical mass spectrum, a smaller signal is observed at a mass 1 amu higher than the molecular ion peak. Why?

A) Due to small impurities in the sample

B) Machine error

C) Because a small percentage of the compound will have a carbon that is the isotope 13C instead of 12C

D) Because of fragmentation

7) Which of the following statements about the base peak of a mass spectrum is always true?

A) The base peak corresponds to the molecular ion.

B) The base peak corresponds to the most abundant ion.

C) The base peak corresponds to the lowest m/z.

D) None of these.

8) What would be the molecular formula of rose oxide which contains C, H, and O and has two degrees of unsaturation and a molecular ion in its mass spectrum at m/z =154?

A) C10H18O

B) C9H14O2

C) C10H2O2

D) C8H10O3

9) Which of the following alkanes gives a significant fragment peak at m/z = 57? 

A) I

B) II

C) III

D) IV

10) 2,2-dimethylbutane gives a significant fragment peak at m/z = 57. Which of the following is the most probable structure of the fragment ion?

A) I

B) II

C) III

D) IV

11) 2,3-dimethylbutane gives a base fragment peak at m/z = 43. Which of the following is the most probable structure of the fragment ion?

A) I

B) II

C) III

D) IV

12) Pentane, C5H12, would have which of the following fragments in its mass spectrum?

       m/z

II    29

III   43

IV   57

A) I

B) II

C) III

D) All of the choices are correct.

13) Hexane, C6H14, would have which of the following fragments in its mass spectrum?

        m/z

I       29

II      43

III     57

A) I

B) II

C) III

D) All of the choices are correct.

14) Heptane, C7H16, would have which of the following fragments in its mass spectrum?

        m/z

I       29

II      43

III     57

A) I

B) II

C) III

D) All of the choices are correct.

15) Butane, C4H10, would have which of the following fragments in its mass spectrum?

        m/z

I       15

II      29

III     57

A) I

B) II

C) III

D) I and II

16) What is the molecular ion, m/z, for the following molecule?

A) 72

B) 70

C) 68

D) 66

17) What is the molecular ion, m/z, for the following molecule?

A) 72

B) 70

C) 68

D) 66

18) What is the molecular ion, m/z, for the following molecule?

A) 72

B) 70

C) 68

D) 66

19) What is the molecular ion, m/z, for the following molecule?

A) 72

B) 70

C) 68

D) 66