SPECTROSCOPY EXAM QUESTIONS WITH ANSWERS #2
What are the 2 types of nmr spectroscopy - correct answer carbon-13
And proton (H1)
Explain what is meant by the fingerprint region of an IR spectrum, and describe how it is
used to confirm the identity of organic molecules [4] - correct answer . The fingerprint
region is the region between 400-1500 cm-1
. And it is UNIQUE FOR ALL COMPOUNDS
. Compare spectrum with that of the known compound
. And it is an EXACT MATCH
Describe a use for NMR spectroscopy in medicine - correct answer magnetic resonance
imaging (MRI)
State the region of the electromagnetic spectrum used in 1H NMR spectroscopy -
correct answer radio waves
Explain why cdcl3 is used as a solvent in 1H NMR spectroscopy - correct answer
because it does not have any protons
- hence won't show on the spectrum
State the chemical responsible for the peak at δ = 0ppm, and state why this chemical
was added to the sample - correct answer . TMS is added
- because its the standard for chemical shift measurements
Compounds in the smoke from forest fires can be analysed using GC-MS. Explain how
GC-MS enables the compounds to be identified - correct answer . GC-MS separates the
compounds
- and the compounds can then be identified, by comparison with a spectral database
Explain how TLC separates compounds in the mixture - correct answer absorption onto
the STATIONARY PHASE
Suggest why it is not possible to conclude that rose oil contains only three different
compounds just from a chromatogram - correct answer compounds have similar Rf
values/adsorptions
Explain how GC-MS can be used to identify these compounds in the rose oil - correct
answer . GC separates the compounds
- and to identify the compounds the MS is compared with a spectral database
How does gas chromatography (GC) separate the compounds in the mixture ? - correct
answer Relative solubility in stationary phase
Compound B is the FIRST TO EMERGE in GC
What are the 2 types of nmr spectroscopy - correct answer carbon-13
And proton (H1)
Explain what is meant by the fingerprint region of an IR spectrum, and describe how it is
used to confirm the identity of organic molecules [4] - correct answer . The fingerprint
region is the region between 400-1500 cm-1
. And it is UNIQUE FOR ALL COMPOUNDS
. Compare spectrum with that of the known compound
. And it is an EXACT MATCH
Describe a use for NMR spectroscopy in medicine - correct answer magnetic resonance
imaging (MRI)
State the region of the electromagnetic spectrum used in 1H NMR spectroscopy -
correct answer radio waves
Explain why cdcl3 is used as a solvent in 1H NMR spectroscopy - correct answer
because it does not have any protons
- hence won't show on the spectrum
State the chemical responsible for the peak at δ = 0ppm, and state why this chemical
was added to the sample - correct answer . TMS is added
- because its the standard for chemical shift measurements
Compounds in the smoke from forest fires can be analysed using GC-MS. Explain how
GC-MS enables the compounds to be identified - correct answer . GC-MS separates the
compounds
- and the compounds can then be identified, by comparison with a spectral database
Explain how TLC separates compounds in the mixture - correct answer absorption onto
the STATIONARY PHASE
Suggest why it is not possible to conclude that rose oil contains only three different
compounds just from a chromatogram - correct answer compounds have similar Rf
values/adsorptions
Explain how GC-MS can be used to identify these compounds in the rose oil - correct
answer . GC separates the compounds
- and to identify the compounds the MS is compared with a spectral database
How does gas chromatography (GC) separate the compounds in the mixture ? - correct
answer Relative solubility in stationary phase
Compound B is the FIRST TO EMERGE in GC
