Chromatography

Question 1

Types of chromatography

Answer 1

Paper chromatography, thin line chromatography, gas chromatography

Question 2

Phases of chromatography

Answer 2

Stationary phase (e.g. paper, doesn’t move), mobile phase (e.g. the solvent that moves)

Question 3

Stationary and mobile phase of paper chromatography

Answer 3

Stationary phase: paper, mobile phase: solvent (e.g. sodium hydroxide)

Question 4

Stationary and mobile phase of thin line chromatography

Answer 4

Stationary phase: thin layer of inert substance (e.g. silica), mobile phase: liquid layer on top (can be aqueous or non-aqueous)

Question 5

Stationary and mobile phase of gas chromatography

Answer 5

Stationary phase: thin layer of inert liquid on silica beads, mobile phase: inert gas

Question 6

Difference between gas chromatography and paper/thin layer chromatography

Answer 6

Gas chromatography is measured using ‘retention time’ on a graph, and the height of the peak represents the strength of the response/how much of each substance there is

Question 7

Retention factor (Rf) equation

Answer 7

Distance travelled / max distance travelled by solvent

Question 8

Factors that affect the Rf in chromatography

Answer 8

Size of molecule (bigger molecules move more slowly)
Polarity (if the molecule has the same polarity as the solvent, it is pulled through faster)