6.3.1 Chromatography And Qualitative Analysis

Question 1

What is the stationary phase

Answer 1

Does not move, solid or liquid supported on solid

Question 2

What is the mobile phase

Answer 2

Does move, liquid or gas

Question 3

Stationary phase of TLC

Answer 3

Silica (adsorbent substance)

Question 4

Stationary phase in gas chromatography

Answer 4

High boiling liquid adsorbed onto inert solid support

Question 5

Mobile phase in gas chromatography

Answer 5

Inert carrier gas (neon or helium)

Question 6

How does gas chromatography work

Answer 6

Inject mixture into apparatus (gas chromatograph)
Mobile carrier gas carries component in sample through column, contains stationary phase
Components slow down as they interact with stationary phase (slower = more soluble)
Retention time = time taken for each component to travel through the column

Question 7

How to interpret a gas chromatogram

Answer 7

Compare retention times to known components
Area under each peak (peak integration) can be used to determine concentration of components in the sample

Question 8

How to determine concentration of components in a gas chromatograph

Answer 8

Prepare standard solutions of known concentrations of the compound
Carry out gas chromatography for these concentrations
Plot calibration curves of peak area against concentration
Obtain a gas chromatogram of compound being investigated
Use calibration curves to measure concentration

Question 9

Test for phenol

Answer 9

Add bromine, white precipitate forms

Question 10

How to test for a carboxylic acid

Answer 10

Add aqueous sodium carbonate, effervescence is a positive result