Question

1. The strength with which an organic compound binds to an adsorbent depends on the strength of the following types of interactions: ion-dipole, dipole-dipole, hydrogen bonding, dipole induced dipole, and van der Waals forces. With silica gel, the dominant interactive forces between the adsorbent and the materials to be separated are_________________.

Answer 1

Dipole-dipole interactions

Step-by-step explanation:

Dipole-dipole interactions occur between two molecules with two polar end- a partially positive end and a partially negative end. The dipoles exists in these molecules due to the difference in the electronegativities of the atoms if the molecule. The positive end of a dipolar molecule will be attracted to the partially negative end of the neighboring molecule.

In the separation of molecules using silica gel as the adsorbent surface, the dominant interactive forces between the adsorbent and the materials to be separated are dipole-dipole interactions. The silica gel have polar SiOH groups on its surface which attracts polar molecules in the material to be separated. These polar molecules are strongly adsorbed to the silica gel surface whereas nonpolar or less polar molecules in the material to be separated are less strongly adsorbed, and thus, are eluted faster than the polar molecules.