Account for the fact that tetrahydrofuran (THF) is very soluble in water, whereas the solubility of diethyl either in water is only \(8 \mathrm{~g} / 100 \mathrm{~mL}\) water.

First, we need to know the molecular structures and formulas of tetrahydrofuran (THF) and diethyl ether. THF is a cyclic ether with the molecular formula C4H8O, while diethyl ether has a molecular formula of C4H10O (CH3CH2-O-CH2CH3).

Next, let's discuss the polarity of both molecules. THF has a more polar oxygen atom due to its bent configuration resulting in a stronger dipole moment than the linear diethyl ether. Water (H2O), being a highly polar molecule itself, has a propensity to dissolve polar molecules. This is due to the intermolecular forces and the ability of water to form hydrogen bonds with other polar molecules.

Water molecules can form hydrogen bonds with other molecules having hydrogen atoms connected to highly electronegative atoms such as oxygen, nitrogen, and fluorine. THF has oxygen-hydrogen part besides the oxygen in the ether part which can form hydrogen bonds with water molecules, whereas diethyl ether doesn't possess any such groups capable of hydrogen bonding with water.

Due to its polar nature and the ability to form hydrogen bonds, THF interacts more effectively with water molecules, resulting in a higher solubility in water. On the other hand, diethyl ether's comparatively nonpolar nature and lack of hydrogen bonding ability make it less soluble in water. This is why the solubility of diethyl ether in water is limited to \(8 \mathrm{~g}/100 \mathrm{~mL}\) water. In conclusion, the high solubility of tetrahydrofuran (THF) in water can be explained by its polar nature and ability to form hydrogen bonds with water molecules, while the low solubility of diethyl ether in water is due to its comparatively nonpolar nature and inability to form hydrogen bonds with water molecules.