Nuclear Magnetic Resonance Spectroscopy

Question 1

what property of the nuclei of atoms allow radiation to be absorbed

Answer 1

some nuclei have magnetic properties. when exposed to a strong magnetic field, they can align themselves with or against the field. When these nuclei are subjected to radio waves, there absorbance coresponds to to the difference in energy between the high and low energy states

Question 2

give two types of NMR

Answer 2

1) Carbon-13 NMR spectroscopy

2) Proton NMR spectroscopy

Question 3

give an example of a solvent used to dissolve the compound into before it is analysed

Answer 3

CCl4

Question 4

what is the standard added

Answer 4

TMS

Question 5

give three advantages of TMS as a standard

Answer 5

• it produces a small single peak that doesn’t interfere with the other peaks. It can be used for comparison
• it has a low boiling point so can easily be removed from the sample afterwards
• it is inert

Question 6

why do different nuclei have different magnetic properties

Answer 6

shielded by different numbers of surrounding electrons

Question 7

which peak is furthest to the left in a C-13 NMR spectrum

Answer 7

the carbon that has the most electronegative environment

Question 8

how many peaks are in a C-13 spectrum of a benzene ring

Answer 8

1- there is only one carbon environment