Chromotography

Question 1

what is chromotography used for

Answer 1

to seperate and identify components in a mixture

Question 2

what are the types of chromatography

Answer 2

column
thin layer chromatography
gas chromatography

Question 3

what is column chromatography

Answer 3

a column is packed with a polar solid and a non polar solvent moves down the column
stationary phase : powder SiO2 or Al2O3
mobile phase : solvent
use : purifying

Question 4

what is TLC

Answer 4

a plate is coated with a polar solid and a non polar solvent moves up the plate
stationary phase : powder SiO2 or Al2O3 on a plastic or glass plate
mobile phase : solvent
use : analysis of solids and liquids

Question 5

what is gas chromatography

Answer 5

a column is packed with a polar solid coated by a liquid and a non polar gas is passed through the column under pressure at a high temperature
stationary phase : powder SiO2 or Al2O3 sometimes coated with a liquid
mobile phase : inert gas e.g Ar or N2
use : analysis of gasses

Question 6

what does higher affinity for stationary phase mean

Answer 6

• higher affinity for the stationary phase this means more attracted to stationary phase so chemical moves slower
  usually polar molecules are attracted to the stationary phase as they are polar so rf is smaller and retention time is longer

Question 7

what does higher affinity to mobile phase mean

Answer 7

higher affinity to mobile phase means more attracted to the mobile phase so the chemical moves faster
usually non polar molecules are attracted to the mobile phase as it is non polar so rf is larger and retention time is shorter

Question 8

what is retention time

Answer 8

time it takes for a compound to travel during chromatography

Question 9

how to calculate rf value

Answer 9

distance from pencil line to dot / total solvent distance

Question 10

what is the developing agent sometimes used called

Answer 10

ninhydrin