Analytical technique

Question 1

Define Rf value.

Answer 1

Rf value is the ratio of the distance travelled by a specific component to the distance travelled by the solvent front.

Question 2

State the mobile phase and stationary phase of gas-liquid chromatography.

Answer 2

Mobile phase: unreactive gas such as N2 and helium.

Stationary phase: non-volatile, non-polar liquid hydrocarbon bonded onto solid support.

Question 3

Define retention time.

Answer 3

The time between injection and detection in which a compound travels through a chromatography column in GLC.

Question 4

Explain why CDCl3 is a better solvent than CHCl3 for use in proton NMR.

Answer 4

CDCl3 will not give an absorption.