Quiz 3 Flashcards
49) Which of the following statements is not true about electromagnetic radiation?
A) The velocity of light is directly proportional to the energy.
B) All molecules absorb electromagnetic radiation at some frequency.
C) Frequency is inversely proportional to wavelength.
D) Energy is directly proportional to frequency.
E) Energy is inversely proportional to wavelength.
A) The velocity of light is directly proportional to the energy.
50) Which of the following regions of the electromagnetic spectrum has the greatest energy per photon?
A) visible
B) microwave
C) radio
D) ultraviolet
E) infrared
D) ultraviolet
51) Which of the following normally occurs in a molecule when a photon of infrared light is absorbed?
A) An electron moves to an orbital of higher potential energy.
B) A transition between allowed vibrational energy states occurs.
C) An electron changes alignment in a magnetic field.
D) The molecule gains an electron.
E) The molecule loses an electron.
B) A transition between allowed vibrational energy states occurs.
54) In the electromagnetic spectrum, ________ frequencies, ________ wavenumbers, and ________ wavelengths are associated with high energy.
A) high, small, long
B) low, large, short
C) low, small, short
D) high, large, short
E) high, small, short
D) high, large, short
61) Which of the following are considered to be bending (in-plane) vibrations?
A) scissoring and wagging
B) scissoring and twisting
C) rocking and wagging
D) rocking and twisting
E) scissoring and rocking
E) scissoring and rocking
62) Which of the following solvents is best used in infrared spectroscopy?
B) II
63) Which of the infrared regions is considered to be the fingerprint region?
A) 4000cm-1 - 1000cm-1
B) 4000μm - 1000μm
C) 2200μm - 1000μm
D) 1000cm-1 - 400cm-1
E) 1000μm - 400μm
D) 1000cm-1 - 400cm-1
64) Which of the following is not a common bending vibration of a CH2 group?
A) flip
B) rock
C) scissor
D) twist
E) wag
A) flip
65) Which of the following increases the absorbance of a solution of phenol in ethanol?
A) increasing the amount of phenol in the solution
B) decreasing the amount of ethanol in the solution
C) decreasing the light path through the solution
D) both A and B
E) both B and C
D) both A and B
67) Which molecule below has a significant band in the IR at 3400 cm-1 (strong and broad)?
A) CH3CH2CH2OH
B) CH3C≡CCH2CH3
C) CH3CH2CH(NH2)CH3
D) (CH3)3N
E) CH3CO2CH2CH3
A) CH3CH2CH2OH
68) Which molecule below has a significant band in the IR at 2220 cm-1 (medium)?
A) CH3CH2CH2OH
B) CH3C≡CCH2CH3
C) CH3CH2CH(NH2)CH3
D) (CH3)3N
E) CH3CO2CH2CH3
B) CH3C≡CCH2CH3
69) Which molecule below has a significant band in the 1720 - 1780 cm-1 range of its IR spectrum?
A) CH3CH2CH2OH
B) CH3C≡CCH2CH3
C) CH3CH2CH(NH2)CH3
D) (CH3)3N
E) CH3CO2CH2CH3
E) CH3CO2CH2CH3
70) Which of the following statements best explains the information we can gain from infrared spectroscopy?
A) It allows us to determine the number of protons in a compound.
B) It allows us to determine the kinds of functional groups in a compound.
C) It allows us to determine the molecular weight and the mass of some fragments of a compound.
D) It allows us to determine the presence and nature of a carbocation in the compound.
E) It allows us to determine the presence and nature of a free radical in the compound.
B) It allows us to determine the kinds of functional groups in a compound.
71) Which compound would be expected to show intense IR absorption at 1715 cm-1?
A) CH3CH2CO2H
B) 1-hexene
C) 2-methylhexane
D) CH3CH2CH2NH2
A) CH3CH2CO2H
72) Which compound would be expected to show intense IR absorption at 1746 cm-1?
A) CH3CH2OCH2CH3
B) CH3CO2CH3
C) CH3CH2CCH
D) CH3CH2SCH3
B) CH3CO2CH3
73) Identify the bond with the lowest wavenumber in the IR spectrum.
A) C=O
B) C-O
C) O-H in alcohol
D) N-H
E) C-H
B) C-O
74) Which of the following wavenumbers corresponds to the bond shown below?
C trriple C
A) 1650 cm-1
B) 2100 cm-1
C) 1100 cm-1
D) 3300 cm-1
E) 2850 cm-1
B) 2100 cm-1
75) Identify the compound that has a formula of C5H10 and bending vibrations at 990 and 910 cm-1.
A) 1-pentene
B) cis-2-pentene
C) trans-2-pentene
D) 2-methyl-1-butene
E) 2-methyl-2-butene
A) 1-pentene
76) At what wavenumber will the C-H stretch involving an sp carbon appear?
A) 2700 cm-1
B) 2900 cm-1
C) 3100 cm-1
D) 3300 cm-1
E) 3500 cm-1
D) 3300 cm-1
77) Which of the following carbonyl groups exhibits the highest wavenumber in infrared spectroscopy?
C) III
78) Which compound’s carbonyl stretch occurs at the greatest wavenumber?
A) CH3CH2CH2CHO
B) CH3COCH2CH3
C) CH3CH2CONH2
D) CH3CH2CO2CH3
E) CH3CH2COCH2CH3
D) CH3CH2CO2CH3
79) Which compound’s carbonyl stretch occurs at the lowest wavenumber?
A) CH3CH2CH2CHO
B) CH3COCH2CH3
C) CH3CH2CONH2
D) CH3CH2CO2CH3
E) CH3CH2COCH2CH3
C) CH3CH2CONH2
84) Which compound has the lowest carbonyl absorption frequency in an infrared spectrum?
A) ester
B) ketone
C) amide
D) aldehyde
E) carboxylic acid
C) amide
85) Which of the following functional groups typically exhibits a carbonyl stretch at the lowest frequency?
A) amide
B) ester
C) ketone
D) aldehyde
E) ether
A) amide
86) Which of the following functional groups will exhibit no IR absorption at 1630 - 1780 cm-1 or at 3200 - 3550 cm-1?
A) an alcohol
B) an amide
C) a ketone
D) an aldehyde
E) an ether
E) an ether
88) In which of the following molecules is the presence of the IR peak for CC not observed?
A
89) Ethyne (HCCH) does not show IR absorption in the region 2000-2500 cm-1 because ________.
A) C-H stretches occur at lower energies
B) CC stretches occur at about 1640 cm-1
C) there is no change in the dipole moment when the CC bond in ethyne stretches
D) there is a change in the dipole moment when the CC bond in ethyne stretches
C) there is no change in the dipole moment when the CC bond in ethyne stretches
90) Which of the following compounds has a vibration that is infrared inactive?
A) CH3—CC—H
B) H2O
C)
D) CO2
E) CO
D) CO2
92) Which compound would be expected to show intense IR absorption at 2710 and 1705 cm-1?
A) CH3COCH2CH3
B) PhCOCH3
C) PhCHO
D) CH2CHCOCH3
C) PhCHO
93) Which compound would be expected to show intense IR absorption at 2250 cm-1?
A) CH3CH2CH2CO2H
B) CH3CH2CH2CN
C) CH3CH2CH2CH2OH
D) CH3CH2CH2CONH2
B) CH3CH2CH2CN
94) Which of the following species has a characteristic absorption at 2200 cm-1 in its IR spectrum?
A) PhCH2CN
B) PhCH2N(CH3)2
C) PhCH2CO2CH3
D) PhCH2CH2OH
E) PhCH2OCH3
A) PhCH2CN
95) Which of the following species has a characteristic broad absorption at 3200-3500 cm-1 in its IR spectrum?
A) PhCH2CN
B) PhCH2N(CH3)2
C) PhCH2CO2CH3
D) PhCH2CH2OH
E) PhCH2OCH3
D) PhCH2CH2OH
96) Which of the following species has a characteristic absorption at 1250 cm-1 in its IR spectrum?
A) PhCH2CN
B) PhCH2N(CH3)2
C) PhCH2CO2CH3
D) PhCH2CH2OH
E) PhCH2OCH3
C) PhCH2CO2CH3
97) Which of the following carbon-hydrogen bonds exhibits the lowest wavenumber for a C—H stretch in infrared spectroscopy?
B
98) Which compound would be expected to show intense IR absorption at 3300 cm-1?
A) CH3CCCH3
B) butane
C) 1-butene
D) CH3CH2CCH
D) CH3CH2CCH
99) Which of the following species has a characteristic absorption at 3300 cm-1 in its IR spectrum?
A) (CH3)2CHCCH
B) (CH3)2CHN(CH3)2
C) (CH3)2CHCCCH3
D) (CH3)2CHCH=CH2
E) (CH3)2CHCO2CH3
A) (CH3)2CHCCH
100) Which molecule below has two significant bands (medium and broad) in the 3300 - 3500 cm-1 range of its IR spectrum?
A) (CH3)3N
B) CH3CH2NH2
C) CH3CH2NH2
D) CH3CON(CH3)2
E) CH3OCH2CH2N(CH3)2
C) CH3CH2NH2
101) Which molecule below has a significant band in the IR at 3300 cm-1 (medium and sharp)?
A) 1-pentene
B) cyclohexane
C) 2-heptyne
D) 1-pentyne
E) diethyl ether
D) 1-pentyne
102) Which molecule below has two significant bands in the IR at 2720 cm-1 and 2820 cm-1 (medium)?
A) CH3COCH2CH
B) CH3CH2CO2CH3
C) CH2=CHCH2CH3
D) CH3CH2CH2CHO
E) CH3CH2CH2OH
D) CH3CH2CH2CHO
109) In the infrared spectrum, a compound of formula C4H8O gave an absorption band at 1720 cm-1, but no bands at 2720 - 2830 and 3400 cm-1. What is the compound?
A) 2-butanone
B) butanal
C) cis-2-butenol
D) trans-2-butenol
E) 1-butenol
A) 2-butanone
111) Identify the compound that has a formula of C4H9N and has one absorption band at 3400 cm-1 and a doublet at 1380 cm-1.
A) diethylamine
B) methylpropylamine
C) isopropylmethylamine
D) butylamine
E) dimethylethylamine
C) isopropylmethylamine
112) Identify the compound that has a formula of C3H6O with a stretching vibration at 1050 cm-1 and an absorption band at 3400 cm-1, but no doublet at 1380 cm-1.
A) 1-propanol
B) 2-propanol
C) ethyl methyl ether
D) propen-1-ol
E) propen-2-ol
A) 1-propanol
113) A mixture of two compounds give absorption bands at 1470, 1595, 1700, 2720, and 2740 cm-1. What compounds are present?
A) aldehyde + benzene
B) ketone + benzene
C) ester + benzene
D) carboxylic acid + benzene
E) anhydrice + benzene
A) aldehyde + benzene
116) Which of the following methods is most suitable for studying conjugation in molecules?
A) infrared
B) NMR
C) mass spectrometry
D) X-ray
E) UV visible
E) UV visible
114) In the UV-visible spectrum of (E)-1,3,5-hexatriene, the lowest energy absorption corresponds to ________.
A) a π to π* transition
B) a σ to π* transition
C) a π to σ* transition
D) a σ to σ* transition
E) a σ to π transition
A) a π to π* transition
115) Absorption of UV-visible energy by a molecule results in ________.
A) vibrational transitions
B) electronic transitions
C) rotational transitions
D) nuclear transitions
E) none of the above
B) electronic transitions
117) Which of the following compounds exhibits the highest λmax in UV spectra?
D) IV
118) Which of the following compounds absorbs the longest wavelength of UV-visible light?
A) (E)-2-butene
B) (Z)-2-butene
C) 1-hexene
D) (Z)-1,3-hexadiene
E) (E)-1,3,5-hexatriene
E) (E)-1,3,5-hexatriene
119) An increase in conjugation is correlated with ________ in the energy of the LUMO, ________ in the energy of the HOMO, and ________ in lmax.
A) a decrease, an increase, a decrease
B) a decrease, an increase, an increase
C) an increase, a decrease, a decrease
D) an increase, a decrease, an increase
E) an increase, an increase, a decrease
B) a decrease, an increase, an increase
An increase in conjugation is correlated with a decrease in the energy of the LUMO, an increase in the energy of the HOMO, and an increase in lmax.
121) Identify the compound with the shortest λmax in an UV spectrum.
A) 1-decene
B) 1,3-decadiene
C) 1,3,5-decatriene
D) 1,4-decadiene
E) 1,3,5,7-decatetraene
A) 1-decene
122) Identify the compound with the longest λmax in an UV spectrum.
A) benzene
B) phenol
C) phenolate ion
D) aniline
E) anilinium ion
C) phenolate ion
123) Which color is observed when a sample absorbs light at 650 nm?
A) yellow
B) orange
C) red
D) violet
E) greenish-blue
E) greenish-blue
124) When a solution of an organic compound absorbs light whose wavelength is 400 nm, the solution appears ________.
A) yellow
B) red
C) purple
D) blue
E) white
A) yellow
125) When a solution of an organic compound absorbs light whose wavelength is 700 nm, the solution appears ________.
A) yellow
B) bluish-green
C) red
D) orange
E) purple
B) bluish-green
126) The pKa of a compound whose acidic or basic form absorbs UV or visible light can be determined spectroscopically since ________.
A) lmax always decreases as acidic form is converted to basic
B) the pKa is the same as the pH at which half of the total absorbance increase occurs
C) absorbance of the basic form is always twice that of the acidic form
D) absorbance of the acidic form is always twice that of the basic form
E) delocalization always leads to a decrease in acidity
B) the pKa is the same as the pH at which half of the total absorbance increase occurs
