Question

8.4 (a) What would be the result of the separation if only hexanes were used as a mobile phase? (b) What would be the result of the separation if only 1:1:hexane:diethyl ether was used as a mobile phase?

Answer 1

@ When only whexane is used as a mobile phase then it is totally non- polar solvent. Non polar groups are moving along the slide. The movement or spot depends up on type of organic compound. If an organic compound contains more non Lpolar groups & if the compound is non polar then RF value of such compds. is high that means compound migrates fastly with mobile phase During monitoring of any reaction n-hexane is used sjost & then is the Rf value is less then polarity of mobile phase increases. I When we use only n-hexane then RF value I is less Due to low RF value no effective seperation of compounds takes place

DATE 6 Now new mobile phase is 1:1 hexane: djethyl ether Here n-hexane is totally non polar & diethyl ethor Lis polar as well as hon polar characteristic. Organic compounds also have some polar & non polar atom or groups. When we use 1:1 n-hexane o djethyl ether then migration of spor is high speed i.e Rl value is more as compared to earlier moblle phase il mixture of n-hexane & diethyl ether can increases the interaction & bonding with organic compound more birmly so that organic compound moves easily with mobile phase & Revale increases. Baric phenomenon behind the is adsorption The compound which adsorbs tightly to stalimaty I phase travel slowly while the compd which adsorb loosely can more with passer speed. I Polarity of solvent lie. mobile phase also causes the Havelling characteris fit of compound When we te 1:1 hexane: djethyl ether then RE value is more. Due to high RF value effective erective Seperation takes place.