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Edexcel A-Level Chemistry: Topic 19 Complete exam 100% Correctly solved
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Edexcel A-Level Chemistry: Topic 19 Complete exam 100% Correctly solved
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Edexcel A-Level Chemistry: Topic 19Complete exam 100% Correctly solved
When is a molecular ion formed? - Answer>>When a molecule
lose an electron
What is very accurate mass spectrometry called? -
Answer>>high resolution mass spectrometry
Why is high resolution mass spectrometry better than normal
mass spectrometry. - Answer>>identify compounds which have
m/z values that round to same nearest whole number
What is NMR for - Answer>>Finding the structure of organic
molecules
What are the 2 types of NMR - Answer>>Carbon 13 NMR High
resolution proton NMR
Explain how NMR works in 3 steps - Answer>>Sample under
strong magnetic field - exposed to different fequencies of
radiwaves
Nuclei absorb diffent amounts of energy because of their
environment
pattern of absorption shows where some atoms are in a molecule
and how many of them their are
What does Carbon 13 NMR show? - Answer>>Number of
carbon atoms and environments they are in
What does high-res proton NMR show - Answer>>number of
protons/hydrogen and environments they are in
, What is meant by an environment in NMR - Answer>>Amount
of electron shielding given by its electrons and the surrounding
molecules
How does the environment affect NMR - Answer>>Nuclei have
different magnetic field in different environment
So absorb different amounts of energy at different frequencies
What are the 3 steps to interpreting a carbon-13 NMR spectra -
Answer>>Count the number of carbon environments (each
peak = 1) (except the peak at 0 which is TMS)
Look at chemical shifts and match to peaks/environments
Try out different possible molecules
Why do peaks in proton NMR spectra split? - Answer>>Only
peaks of those attached to Carbon split
Splitting is caused by hydrogens on adjacent carbon atoms, this is
called *spin-spin coupling*
What are the split peaks on proton NMR spectra called -
Answer>>Multiplets
How do you determine how many a peak will split into in proton
NMR spectra? - Answer>>n+1 rule count number of hydrogen
on adjacent carbons, add 1 and this is amount of new peaks
What does the area of under proton NMR show you? -
Answer>>Relative area shows relative amount of hydrogen in
each environment
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