CHEM 233 FINAL EXAM - POSTLAB QUESTIONS AND
CORRECT DETAILED ANSWERS (VERIFIED ANSWERS)
|ALREADY GRADED A+||BRAND NEW!
Electrospray ionization is a soft ionization technique.
true
false Ans✓✓✓true
Spectra with one chlorine atom Ans✓✓✓ratio of the two lines will be
3:1
Spectra with one bromine atom Ans✓✓✓ratio of the two lines will be
1:1
Neutral Molecular Weight of 102 g/mol Ans✓✓✓anything with 103 or
125
A non polar bond will always show signal in the IR Spectra
true
false Ans✓✓✓false (dipole moment needs to be present)
Increasing the mass of atoms connected by a bond results in the
absorbance of a higher wavenumber of light.
,true
false Ans✓✓✓false
Select the bond that would absorb the highest wavenumber of light in an
IR experiment.
C-N single bond
C-N double bond
C-N triple bond
Cannot be determined Ans✓✓✓C-N triple bond
Which of the following wavenumber ranges corresponds to the
fingerprint region in an IR spectrum? Ans✓✓✓<1500 cm-1
Which of the following structures would you expect to have a carbonyl
stretch above 1700 cm-1 in an IR spectrum? Select all that apply.
Ans✓✓✓Most carbonyls will have stretches above 1700 cm-1. Only
carbonyls possessing contributing resonance structures, namely amides
and conjugated carbonyls, will have stretches below 1700 cm-1.
IR spectra for a C-H Carbon that is sp hybridized Ans✓✓✓3300 cm-1
When placed inside of a magnetic field, NMR active nuclei act in what
way?
,They align mostly in the same direction as the applied magnetic field
They randomly align
They align with and against the applied magnetic field in a 1:1 ratio
They align mostly in the opposite direction of the applied magnetic field
Ans✓✓✓They align mostly in the same direction as the applied
magnetic field
When placed inside of a magnetic field, the magnetic field that electrons
generate aligns in the opposite direction of the applied magnetic field.
This has what effect on the nucleus the electrons are around?
The electrons have no effect on how the nucleus interacts with the
magnetic field
The electrons shield the nucleus from the magnetic field
The electrons react with the nucleus
The electrons better expose the nucleus to the magnetic field
Ans✓✓✓The electrons shield the nucleus from the magnetic field
, The nitrogen in the compound below has what kind of effect on nearby
hydrogens? (1 pt)
deshielding
shielding
no effect Ans✓✓✓deshielding
Coupling Ans✓✓✓In NMR spectroscopy, a phenomenon that occurs
when there are protons in such close proximity to each other that their
magnetic moments affect each other's appearance in the NMR spectrum
by subdividing their peaks into subpeaks; also called splitting.
A carbon carbon triple bond would contribute how many degrees of
unsaturation to a molecule? Ans✓✓✓2
How many degrees of unsaturation are present in a molecule with the
molecular formula C5H8BrNO? Ans✓✓✓2
You wish to analyze the purity of a compound via TLC. If you wanted
polar compounds to remain near the bottom (baseline) of the plate, what
kind of TLC plate would you use? (1 pt)
CORRECT DETAILED ANSWERS (VERIFIED ANSWERS)
|ALREADY GRADED A+||BRAND NEW!
Electrospray ionization is a soft ionization technique.
true
false Ans✓✓✓true
Spectra with one chlorine atom Ans✓✓✓ratio of the two lines will be
3:1
Spectra with one bromine atom Ans✓✓✓ratio of the two lines will be
1:1
Neutral Molecular Weight of 102 g/mol Ans✓✓✓anything with 103 or
125
A non polar bond will always show signal in the IR Spectra
true
false Ans✓✓✓false (dipole moment needs to be present)
Increasing the mass of atoms connected by a bond results in the
absorbance of a higher wavenumber of light.
,true
false Ans✓✓✓false
Select the bond that would absorb the highest wavenumber of light in an
IR experiment.
C-N single bond
C-N double bond
C-N triple bond
Cannot be determined Ans✓✓✓C-N triple bond
Which of the following wavenumber ranges corresponds to the
fingerprint region in an IR spectrum? Ans✓✓✓<1500 cm-1
Which of the following structures would you expect to have a carbonyl
stretch above 1700 cm-1 in an IR spectrum? Select all that apply.
Ans✓✓✓Most carbonyls will have stretches above 1700 cm-1. Only
carbonyls possessing contributing resonance structures, namely amides
and conjugated carbonyls, will have stretches below 1700 cm-1.
IR spectra for a C-H Carbon that is sp hybridized Ans✓✓✓3300 cm-1
When placed inside of a magnetic field, NMR active nuclei act in what
way?
,They align mostly in the same direction as the applied magnetic field
They randomly align
They align with and against the applied magnetic field in a 1:1 ratio
They align mostly in the opposite direction of the applied magnetic field
Ans✓✓✓They align mostly in the same direction as the applied
magnetic field
When placed inside of a magnetic field, the magnetic field that electrons
generate aligns in the opposite direction of the applied magnetic field.
This has what effect on the nucleus the electrons are around?
The electrons have no effect on how the nucleus interacts with the
magnetic field
The electrons shield the nucleus from the magnetic field
The electrons react with the nucleus
The electrons better expose the nucleus to the magnetic field
Ans✓✓✓The electrons shield the nucleus from the magnetic field
, The nitrogen in the compound below has what kind of effect on nearby
hydrogens? (1 pt)
deshielding
shielding
no effect Ans✓✓✓deshielding
Coupling Ans✓✓✓In NMR spectroscopy, a phenomenon that occurs
when there are protons in such close proximity to each other that their
magnetic moments affect each other's appearance in the NMR spectrum
by subdividing their peaks into subpeaks; also called splitting.
A carbon carbon triple bond would contribute how many degrees of
unsaturation to a molecule? Ans✓✓✓2
How many degrees of unsaturation are present in a molecule with the
molecular formula C5H8BrNO? Ans✓✓✓2
You wish to analyze the purity of a compound via TLC. If you wanted
polar compounds to remain near the bottom (baseline) of the plate, what
kind of TLC plate would you use? (1 pt)
