1.	The 1H NMR spectrum of X with molecular formula C3H6O is shown below.

(a)	Deduce which of the following compounds is X and explain your answer.
		CH3–CO–CH3	CH3–CH2–CHO	CH2=CH–CH2OH
	Compound:
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	Explanation:
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(2)

(b)	Deduce which one of the peaks in the 1H NMR spectrum of X would also occur in the spectrum of one of the other isomers, giving your reasoning.
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(2)
 
(c)	The infrared and mass spectra for X were also recorded.
(i)	Apart from absorptions due to C–C and C–H bonds, suggest one absorption, in wavenumbers, that would be present in the infrared spectrum.
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(1)
 
(ii)	Apart from absorptions due to C–C and C–H bonds, suggest one absorption, in wavenumbers, absent in this infrared spectrum but present in one of the other compounds shown in part (a).
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(1)
 
(d)	Suggest the formulas and m/z values of two species that would be detected in the mass spectrum.
Species: .......................................................................................................................
m/z: .............................................................................................................................
Species: .......................................................................................................................
m/z: .............................................................................................................................
(2)
(Total 8 marks)

2.	Selected regions of the electromagnetic spectrum are represented in order of increasing frequency below.

(a)	Identify region A.
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(1)
 
(b)	Identify the atomic or molecular processes associated with microwave and ultraviolet radiation.
	Microwave:
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	Ultraviolet:
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(2)
 
(c)	State which region of the electromagnetic spectrum can be used to identify the functional groups present in a molecule.
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(1)

(d)	Explain why the absorptions in infrared (IR) spectroscopy occur at much higher frequency than those in 1H NMR spectroscopy.
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(2)
(Total 6 marks)

3.	Infrared spectroscopy is commonly used as an analytical technique by inorganic, physical and organic chemists.
(a)	Explain why hydrogen bromide is IR active whereas bromine is IR inactive.
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(1)
 
(b)	The IR spectrum, mass spectrum and 1H NMR spectrum of an unknown compound, X, of molecular formula C5H10O2, are as follows.

 
  
	[Source: SDBSWeb:http://riod01.ibase.aist.go.jp/sdbs/(National Institute of Advanced Industrial Science and Technology)]

(i)	In the IR spectrum, identify the bond responsible for each of the absorptions labelled I, II and III.
I: ......................................................................................................................
II: .....................................................................................................................
III: ....................................................................................................................
(3)
 
(ii)	In the mass spectrum, deduce which fragments the m/z values at 102, 57 and 45 correspond to.
m/z = 102: .........................................................................................................
m/z = 57: ...........................................................................................................
m/z = 45: ...........................................................................................................
(3)
 
(iii)	Identify the peak at 11.5 ppm in the 1H NMR spectrum.
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(1)
 
(iv)	State what information can be obtained from the integration traces in the 1H NMR spectrum about the hydrogen atoms responsible for the peak at 1.2 ppm.
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(1)

(v)	Deduce the structure of X.

(1)
 
(vi)	CH3COOCH2CH2CH3 is an isomer of X. Deduce two differences between the
1H NMR spectrum of this isomer and that of X.
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(2)
(Total 12 marks)

4.	The IR spectrum, mass spectrum and 1H NMR spectrum of an unknown compound, X, of molecular formula C3H6O2 are as follows.

	[Source: SDBSWeb: http://riodb01.ibase.aist.go.jp/sdbs/ (National Institute of Advanced Industrial Science and Technology)]

(i)	Identify the bonds responsible for the peaks A, B and C in the IR spectrum of X.
A: .................................................................................................................................
B: .................................................................................................................................
C: .................................................................................................................................
(2)
 
(ii)	In the mass spectrum of X, deduce which ions the m/z values at 74, 45 and 29 correspond to.
m/z = 74: ......................................................................................................................
m/z = 45: ......................................................................................................................
m/z = 29: ......................................................................................................................
(3)
 
(iii)	Identify the peak at 11.73 ppm in the 1H NMR spectrum.
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(1)
 
(iv)	Deduce the structure of X.

(1)
(Total 7 marks)

5.	Explain what occurs at a molecular level during the absorption of infrared (IR) radiation by the sulfur dioxide molecule, SO2.
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(Total 3 marks)

6.	Consider the IR spectra of the following three compounds.
	A = CH3(CH2)3COOH
	B = CH3COOC(CH3)3
	C = (CH3CH2)3COH

	Determine which IR spectrum corresponds to each compound A, B and C. Explain your reasoning. IR data can be found in Table 17 of the Data Booklet.

Compound	Spectrum	Reason	
A	...........	.............................................................................................
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B	...........	.............................................................................................
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C	...........	.............................................................................................
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(Total 5 marks)

7.	A feature of some 1H NMR spectra is the electron-withdrawing effect of electronegative atoms. These atoms cause nearby protons to produce peaks at higher chemical shift values, often in the range 2.5 to 4.5 ppm.
Consider the 1H NMR spectrum of an unknown compound, D, which has a molecular formula C4H8O2 and is known to have an absorption in its IR spectrum corresponding to a C=O absorption.

	Use this information and the values in Table 18 of the Data Booklet to deduce the structure of D.
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(Total 4 marks)

8.	Mass spectrometry is a powerful analytical technique used in the identification of organic compounds. The mass spectrum of a compound with empirical formula CH2O displays peaks at m/z 15, 45 and 60.
(a)	Determine the molecular formula of the compound.
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(1)
 
(b)	Identify the fragments responsible for the peaks at
m/z = 15 .......................................................................................................................
m/z = 45 .......................................................................................................................
(2)

(c)	Identify a compound that could produce this spectrum.
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(1)
(Total 4 marks)

9.	The infrared spectrum of a substance, X, with empirical formula C3H6O is given below.
		
[Source: NIST http://webbook.nist.gov/chemistry]
 
(i)	Explain why the structural formula of X cannot be:
		
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(2)
 
(ii)	The 1H NMR spectrum of X consists of three peaks. Deduce the structural formula of X and the relative areas under each peak.

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(2)
(Total 4 marks)

10.	1H NMR and IR spectroscopy both involve the absorption of electromagnetic radiation.
(a)	(i)	Identify the region of the electromagnetic spectrum used in 1H NMR spectroscopy.
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(1)
 
(ii)	Identify which of these two techniques involves higher energy radiation.
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(1)
 
(b)	Identify which of the following molecules absorbs IR radiation and explain your choice.
		H2        O2        HCl
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(2)
(Total 4 marks)

11.	(a)	The mass spectrum of an unknown compound, X, of empirical formula C2H4O is shown below.

[Source: Cleapss Guides: L202 Spectra (Cleapss School Science Service), Sept 2000.]
 
(i)	Determine the relative molecular mass of X from the mass spectrum and deduce the formula of the molecular ion.
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(2)
 
(ii)	Identify a fragment which gives rise to the peak at m/z = 29.
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(1)
 
(iii)	Comment on the absence of a peak at m/z = 59.
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(1)

(b)	The IR spectrum of X is shown below.

[Source: http://modbo1.ibase.go.jp/sdbs/cgi-bin/cre_index.cgi?lang=eng]
 
(i)	Use Table 17 of the Data Booklet to identify the bonds which correspond to the absorptions A and B.
A: ......................................................................................................................
B: ......................................................................................................................
(1)
 
(ii)	Deduce the name of the functional group present in X.
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(1)
 
(c)	(i)	The 1H NMR spectrum of X shows three peaks. State the information that can be obtained from the number of peaks.
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(1)

(ii)	The 1H NMR spectrum of X includes peaks at 2.0 and 4.1 ppm. Use Table 18 of the Data Booklet to suggest the chemical shift of the third peak and state its relative peak area. Show your answers in the table below.

Peak	Chemical shift / ppm	Relative peak area	
First	2.0	3	
Second	4.1	2 	
Third			
(2)
 
(iii)	Deduce a possible structure for X that is consistent with the mass, IR and 1H NMR spectra.

(1)
(Total 10 marks)

12.	Compounds A and B are alcohols with the molecular formula C3H8O. The following information was obtained from a mass spectrum of each alcohol.
A:	peaks at m/z = 29, 31, 60
B:	peaks at m/z = 45, 60
(a)	Deduce the formula of the species responsible for the peak at m/z = 60.
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(1)
 
(b)	Deduce the formula of the species with m/z = 31.
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(1)

(c)	Deduce the structure of each alcohol.
	Structure of A

	Structure of B

(2)
(Total 4 marks)