(c) Chemical analysis Flashcards

1
Q

What is chromatography?

A

A technique used for analysis.

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2
Q

What are the 2 phases in chromatography?

A

Mobile and stationary phase.

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3
Q

What are the 4 types of chromatography?

A
  1. Paper
  2. Thin layer (TLC)
  3. Gas
  4. HPLC (High Performance Liquid)
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4
Q

What is the stationary phase in paper chromatography?

A

Paper.

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5
Q

What is the mobile phase in paper chromatography?

A

Solvent.

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6
Q

If a substance is soluble in the solvent what will this mean for the distance it will travel?

A

It will travel further.

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7
Q

Substances which have a higher affinity for the stationary phase will travel …?

A

Less far.

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8
Q

What is the stationary phase in thin layer chromatography?

A

Glass with a thin layer of cellulose or silica.

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9
Q

What is the mobile phase in thin layer chromatography?

A

Solvent.

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10
Q

Why is thin layer chromatography better than paper?

A

The mobile phase move more quickly through the stationary phase.
The mobile phase moves more evenly through the stationary phase.
There is a range of absorbencies for the stationary phase.

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11
Q

What are the 2 things that affect how far molecules move in chromatography?

A

Size and polarity.

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12
Q

Will bigger molecules move farther or shorter than smaller molecules?

A

Larger molecules will take longer to move whereas the smaller molecules are more mobile.

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13
Q

If a polar solvent is used which type of molecules will move further and why?

A

Polar molecule will move further as they are more strongly attracted to the solvent than non-polar molecules.

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14
Q

What is the RF value?

A

The distance that a certain spot moved in comparison to the overall distance that the solvent moved.

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15
Q

What is the formula to work out the Rf value?

A

Distance traveled by component/

distance traveled by solvent

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16
Q

What is the retention time?

A

The retention time of a solute is the elapsed time between the time of injection of the solute and the time of elution of the peak maximum of that solute.