Simulation
EXPLANATION:
The simulation experiments offer information to the students that Rf value of the analyte increases and decreases with the rise and decrease of the polarity of the solvent system for the same stationary phase.
The solvent system is an organic solvent or mixture of different organic solvents. As the solvent system moves over the surface of the stationary phase, it transports the analyte over the particles of the stationary phase. Therefore, if a highly polar solvent is used, it will interact strongly with the surface of the stationary phase and will leave only few sites on the stationary phase free to bind with the analyte. The analyte will, therefore, move quickly over the stationary phase. Similarly, polar groups in the solvent can interact strongly with polar functionality in the analyte and prevent interaction of the analyte with the surface of the stationary phase. These effects lead to rapid movement of the analyte over the stationary phase.
The polarity of a solvent system to be used for chromatography is evaluated by examining the dielectric constant () and dipole moment () of the solvent. The larger these two numbers, the more polar is the solvent. In addition, the hydrogen bonding ability of the solvent is also considered.