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A-level Chemistry (AQA) > Chromatography > Flashcards

Chromatography Flashcards

1
Q

What is the stationary phase?

A

molecules cannot move through

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2
Q

What is the mobile phase?

A

molecules can move through

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3
Q

Describe TLC

A
  • piece of glass coated in silica gel (SP)
  • sample dropped onto line on TLC plate
  • TLC plate put into solvent (MP)
  • when dry observed under UV light.
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4
Q

What is the MP in TLC

A

the solvent

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5
Q

What is the SP in TLC

A

silica gel

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6
Q

describe solubility and affinity for TLC

A

the further up the the sample has travelled the more soluble it is in MP and has low affinity in the SP

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7
Q

adv of TLC

A

faster
works on small samples

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8
Q

disadv of TLC

A

cannot be use to separate large amounts

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9
Q

How to calculate Rf value

A

distance moved by component/distance moved by solvent

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10
Q

Describe column chromatography

A
  • column packed with silica (SP)
  • pour mixture in column.
  • solvent poured on top (MP)
  • diff components travel down at diff rates - one reaches the bottom and be collected off (next can be collected off sometime later)
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11
Q

adv of CC

A

can be used to separate large quantities

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12
Q

what does higher charges mean in terms of polarity of a molecule

A

molecule is more polar

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13
Q

What is the MP in CC

A

solvent

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14
Q

What is the SP in CC

A

silica

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15
Q

what is GLC used for

A

to separate mixture of volatile components

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16
Q

describe GLC

A
  • carrier gas (helium/nitrogen) flows through capillary column (MP)
  • Column lined with gel (SP)
  • sample injected through column
  • carrier gas transports components along until detector reached where a current is produced
  • retention time measured
17
Q

What is the MP in GCL

A

carrier gas

18
Q

What is the SP in GCL

A

coating of gel

19
Q

what is retention time

A

how long it takes for the component to move from the point of injection to the detector.

20
Q

limitations of GCL

A

Chromatogram produces many peaks

A-level Chemistry (AQA) (26 decks)

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