Chromatography

Question 1

What are the three types of chromatography?

Answer 1

Thin-layer, column, and gas-liquid

Question 2

What is the equation for calculating the Rf value?

Answer 2

Distance travelled by component / Distance travelled by solvent

Question 3

TLC Chromatography

Answer 3

1. Base line drawn in pencil 1cm from bottom of plate
2. Different mixtures spotted onto base line with capillary tube at different distances
3. Plate placed into beaker containing solvent (solvent must not go above base line) with a watch glass over the top to keep the environment saturated
4. The solvent should rise until 1cm from the top
5. Remove the plate and immediately mark solvent front with pencil
6. UV lamp used after plate is dry to determine where spots are. Circle these with pencil
7. Calculate Rf values

Question 4

GLC Chromatography

Answer 4

Used for gases, volatile liquids and solids in vapour form
1. Sample injected in long coiled column through a self-sealing disc
2. Inert gas carries sample through column
3. Passed to detector which records retention time

Question 5

Column Chromatography

Answer 5

Long, vertical glass tube or burette is used as the column
1. Inert solid placed in column
2. Liquid solvent added in until fully saturated
3. Sample mixture dissolved in solvent and added to top of column
4. More solvent added on top of this to stop it drying out
5. Component with greatest attraction to inert solid takes longest time to move through column