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#A2 Chemistry > 1.Analysis > Flashcards

1.Analysis Flashcards

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1
Q

Typesa of analysis?

A
  • infrared spectrum
  • mass spectro
  • NMR
  • chromatography
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2
Q

Spin and a magnetics field effect on it

A

spun in either of two directions normalls of same energy level

if you put the neuclues in amagnetic field then the spin directions have different energy (as oes field is witht he big field)

this energy difference can be picked up by firing em radion at it

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3
Q

what must neucli have for NMR

A

odd number of protons/neutrons

as the unpaired one will produce a residual magnetic field

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4
Q

NMR resonance

A

the enrergy difference between the two states

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5
Q

type of em radiation used in NMR

A

radio waves

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6
Q

what is chemical shift (little delta)

A

a scale that compares the frequency of an NMR absorbtion with the frequency of the reference peak of TMS

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7
Q

what is chemical shift measured in?

A

perts per million (ppm)

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8
Q

what is cmemical shift of C and H measured relative to?

A

TMS , or (CH3)4Si

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9
Q

whys is tms used?

A

chemically unreactive and volatile

as the C13 , H1 and (Si29) all only have one environment

(added in with the sample)

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10
Q

what is chemical shift effected by?

A
  • electronegative atoms nearby
  • pi bonds nearby

Higer value in table always wins

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11
Q

what solvents must be used for NMR?

A

deuterated solvents.

D is a H with another neutron

CDCl3 is used as the solvent

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12
Q

why is CDCl3 used as the solvent?

A

as the peak will always be in the same place so can be removesd, and hydrogen has no peak.

The solvent can be evaporated off to recover the sample

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13
Q

what can you get from carbon NMR?

A
  • numbe rof environments
  • type of environment
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14
Q

whatc can u tell from hydrogen NMR?

A
  • number of environments
  • type of environment
  • proportion of hydroens in each environment
  • adjacent protons
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15
Q

what is an integration trace

A

a line that increases in height as it passes each peak, shows the ratio in each peak.

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16
Q

what is spin spin coupling and what causes it

A

the splitting of peaks caused by the magnetic interaction of neibouring hydrogens either lined with or against the hydrogen.

(only between hydrogens of different environment)

17
Q

SSC names

A
  1. Singlet
  2. Doublet
  3. Triplet
  4. Quartet
    • multiplet
18
Q

how to predict splitting pattern

A

n+1 rule ( in pattern of pascals triangle)

19
Q

whats annoying about -OH and -NH NMR

A

the peaks will be over a very wide range of delta values

20
Q

what does D2O do?

A

makes -OH and -NH hydrogen peaks disappear

as the H becomes a D

21
Q

Do -OH and -NH peaks split?

A

nope

as the OH forms broad peaks as hydrogen bonding happens

22
Q

NMR uses?

A
  • medicine
  • body scanning
23
Q

what is partition cromatography?

A
  • mobile phase is a liquid or gas
  • stationary pahsae is a non volatile liquid
  • distributed by solubility
24
Q

what is adsorbtion chromatography?

A
  • mobile phas eis a liquid or gas
  • stationary pahse is solid
  • they adsorb onto the solid surface
25
Q

what is paper chromatography?

A
  • partition types
  • stationary phgase is water
  • mobile is solvent
26
Q

what is thin layer chroma

A
  • adsorbtion type
  • mobile phase is solvent
  • stationary is the surfact of SiO2/Al2O3 on inert glass sheet
27
Q

what id Rf

A

distance travelled by compound/distance by solvent

28
Q

how does a solid stationary pahse seperate?

A

by adsorbtion

29
Q

how does a liquid stationary phase seperate?

A

by solubility

30
Q

limitations of tlc

A
  • similar compounds has similar Rf
  • Unkowns have no Rf
  • Hard to find a solvent that seperates all compounds in a mizture
31
Q

gas liquid chromatography?

A
  • stationary phase is a thin layer of solid/liquid
  • mobile phase is a carrier gas. something unractive like helium
  • you measure the time not the distance and get retention time
  • Moves more if its more volatile and less soluble(/adsorbtion)
  • partiion type
32
Q

GLC setup

A
  • 30m long inert capillary tubing
  • inside a controlled oven
  • usually feeds into mass spectrum after detection.
33
Q

glc limitations?

A
  • could have some retention time
  • substances could avoid detection
  • unknows have no known retention time
34
Q

why is gas chromas , mass spectrum good?

A

cause the gas chroma will seperate the mixture

the mass spectrum will help identify it

35
Q

uses for GS-MS

A
  • forensics
  • environmental analysis
  • airport security
  • space probes
36
Q

Getting proportions freom GS

A

Use the relative peak areas

37
Q

What is retention time

A

The time from the injection of the samplefor the compound to leave the column

#A2 Chemistry (14 decks)

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