Spectroscopy

Question 1

write eqn to show how nonane is converted to their molecular ions

Answer 1

C9H20 -> C9H20+ + e-

Question 2

explain why there is a peak in the spectrum after the molecular ion peak

Answer 2

the M + 1 peak arises as there is a small % of carbon-13 isotope in the sample and this adds one to the Mr of the molecular ion

Question 3

common peaks

Answer 3

15 = CH3+
29 = CH3CH2+
31 = CH2OH+
45 = CH3CH2O+ COOH+

Question 4

Write an eqn for the formation of the fragment ion CH3CH2CH2 from hexan-2-one molecular ion

Answer 4

CH3CH2CH2CH2COCH3+ -> CH3CH2CH2+ + CH2COCH2.

Question 5

Name the two types of vibrations caused by infrared radiation in molecules

Answer 5

stretching and bending

Question 6

how do we identify between two structural isomers using the mass spectrum

Answer 6

look at the m/z of highest peak to identify a definite fragment