Idenitfying compounds

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  • Created by: Sopha8
  • Created on: 27-05-15 20:17
Explain what happens at the detector of a mass spectrometer
ion hits detector causing current to flow, bigger current= higher abundance
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What are the M, M+1 and M+2 peaks on a mass spectrum of a compound?
M=Mr of compound, highest peak thats on the right. M+1-caused by c-13 isotope, found right of M peak. M+2=Cl or Br in compound, Cl-35 most abundant so in M peak, Cl-37 ratio of 3:1 to M peak. Br-79 and 81 are same height
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How can you work out the number of carbon atoms in a compound from its mass spec?
no.C=height M+1 peak/ height M peak X 100
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How do you predict the number of molecular ion peaks?
add up possible combinations of isotopes
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What is used a a standard for N.M.R and why?
trimethlysilate- Si(CH3)4. reason=single peak futher right than any other, inert, non-toxic and volatile so easily removed
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What can be deduced from a C-13 or H-1 N.M.R spectrum?
C-13 each peak is a carbon evironment. H-1, peak for each H environement, height tells number of H atoms in that environment and splitting pattern shows how many H on adjacent carbon
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What solvent can be used to dissolve a sample before using N.M.R?
CCl4 or CDCl3 as they dont produce peak. CDCl3 may be used over CCl as its polar
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Describe column chromatography
Sample put into glass column with slurry in (stationary phase) then washed out using solvent (mobile phase). Idenitify components by retention time, more soluble to mobile stage=quickest to travel
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Describe gas-liquid chromatography, what is it used for?
for volatile liquids (turn to gas easily). sample vaporised and injected into tube, coated with viscous liquid (stationary phase) and built in an oven, with unreactive carrier gas (mobile phase). retention time= time from being injected to detected
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Other cards in this set

Card 2

Front

What are the M, M+1 and M+2 peaks on a mass spectrum of a compound?

Back

M=Mr of compound, highest peak thats on the right. M+1-caused by c-13 isotope, found right of M peak. M+2=Cl or Br in compound, Cl-35 most abundant so in M peak, Cl-37 ratio of 3:1 to M peak. Br-79 and 81 are same height

Card 3

Front

How can you work out the number of carbon atoms in a compound from its mass spec?

Back

Preview of the front of card 3

Card 4

Front

How do you predict the number of molecular ion peaks?

Back

Preview of the front of card 4

Card 5

Front

What is used a a standard for N.M.R and why?

Back

Preview of the front of card 5
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