Rf Values and Chromatography

A high R_f value indicates strong

• strong affinity to the stationary phase
• strong affinity to the mobile phase
• no affinity to the stationary phase
•  no affinity to the stationary phase

A student extracts the colour from some green smarties and uses paper chromatography to separate components colours. She finds blue has a R_f =0.38 and yellow R_f =0.75 this suggests 

• the yellow is more strongly adsorbed onto the stationary phase and is less solublein the mobile phase.
• the yellow is more strongly adsorbed onto the stationary phase and is more soluble in the mobile phase.
• the blue is more strongly adsorbed onto the stationary phase and is less solublein the mobile phase.
• the blue is more strongly adsorbed onto the stationary phase and is less solublein the mobile phase.

A high R_f value indicates strong

• strong affinity to the stationary phase
• strong affinity to the mobile phase
• no affinity to the stationary phase
•  no affinity to the stationary phase

The R_f value  for the blue component is 

• 0.3
• 0.7
• 10
• 3

The R_f value  for the red component is 

• 0.3
• 0.7
• 10
• 7

The retention factor is used

• to zero the chromatography scale
• to identify unknown compounds in a sample
• to retain solvent
• as a starting tool for chromatography

A characteristic feature of any form of chromatography is the ...

• calculation of an Rf value for the molecules separated.

• use of an inert carrier gas.

• use of a mobile and a stationary phase.

• use of molecules that are soluble in water.