Chromatography (Organic) (complete)

Question 1

Name the three different types of chromatography.

Answer 1

• Column chromatography
• Gas-liquid chromatography
• Thin-layer chromatography

Question 2

What is separated using column chromatography?

Answer 2

• large quantities of soluble substances

Question 3

what is separated using gas-liquid chromatography?

Answer 3

mixtures of volatile liquids.

Question 4

How/why does separation take place in chromatography?

Answer 4

• because the substances in a mixture have a different affinity for the stationary phase and mobile phase.

Question 5

What is retention time?

Answer 5

• the time is takes for a substance to pass through the column in chromatography

Question 6

What is the stationary and mobile phase for column chromatography?

Answer 6

Stationary - powder (silicon dioxide or aluminium oxide) and often packed into the glass column.
Mobile - solvent

Question 7

What is the stationary and mobile phase for Gas-liquid chromatography?

Answer 7

Stationary - powder coated with a film of a non-volatile liquid. (silicon dioxide or aluminium oxide)
Mobile - unreactive gas (nitrogen, helium or hydrogen)

Question 8

What is the stationary and mobile phase for TLC chromatography?

Answer 8

Stationary - silicon dioxide or aluminium oxide powder
Mobile - solvent

Question 9

How does Gas-Liquid chromatography work?

Answer 9

The stationary phase is packed into a long,narrow steel tube and the tube is coiled up.
The sample if injected into the column, and a continuous flow of the mobile phase passes through the column.
The substances are separated as they travel through the plumb depending on their affinity for the stationary and mobile phase.
The chromatogram shows the time it takes for each substance to pass through the column. The size of the signal is proportional to the amount of substance in the mixture.

Question 10

How does column chromatography work?

Answer 10

The mixture is dissolved in the solvent and placed at the top of the column. As the solvent moves down the column, the substances in the mixture move the column at different rates depending on their affinity to the stationary and mobile phase, allowing them to be collected separately at the bottom.

Question 11

Give the equation for retention factor

Answer 11

distance moved by samples / distance moved by mobile phase (solvent)

Question 12

How can you identify some substances that are not visible in normal conditions after a TLC chromatography?

Answer 12

• Add ninhydrin to amino acids, and they will stain.
• Shine UV light over the samples and they will glow.