Which molecule would you expect to be more soluble in water: CH₃CH₂CH₂OH or HOCH₂CH₂CH₂OH?

Key Concepts

Polarity of Molecules

Polarity refers to the distribution of electrical charge over the atoms in a molecule. Polar molecules, which have a significant difference in electronegativity between their atoms, tend to interact favorably with water, a polar solvent. In contrast, nonpolar molecules do not dissolve well in polar solvents due to their lack of charge separation.

Hydrogen Bonding

Hydrogen bonding is a strong type of dipole-dipole interaction that occurs when hydrogen is bonded to highly electronegative atoms like oxygen or nitrogen. Molecules capable of forming hydrogen bonds with water can enhance their solubility. The presence of hydroxyl (-OH) groups in a molecule increases its ability to form hydrogen bonds with water.

Hydrophobic vs. Hydrophilic Interactions

Hydrophobic interactions occur between nonpolar molecules that repel water, while hydrophilic interactions involve polar or charged molecules that attract water. Molecules with long nonpolar hydrocarbon chains are typically hydrophobic, reducing their solubility in water. In contrast, molecules with more polar functional groups are hydrophilic and tend to dissolve better in aqueous environments.