Question

Alcohols are comparatively more soluble in water than hydrocarbons of comparable molecular masses. Explain this fact.

Answer 1

To begin addressing this, we must first understand what polar solvents are, let's start with polar solvents: Polar solvents are identified by the significant size difference between them; as a result, there is a minor movement of the electron pairs on the side of the electronegative atom, resulting in a molecule with a partially positive and partially negative charge. This is because the two atoms' electronegativity differs significantly from one another. To start, it's important to understand that like dissolves like, meaning that polar solutes will dissolve in polar solvents and nonpolar solutes will dissolve in nonpolar solvents. Water is known as the "universal solvent" since it dissolves more substances than any other liquid, which is why we also need to know what kind of solvent it is. The hydrogen and oxygen atoms in water molecules are arranged polarly, with hydrogen having a positive electrical charge and oxygen having a negative charge. Alcohols may make hydrogen bonds with water because the -OH group is present, but hydrocarbons are unable to do so since the -OH group is not present. Alcohols therefore have a higher solubility in water than hydrocarbons with similar molecular weights. Because the contact happens between the two separate atoms that comprise the solute and solvent in this case, intramolecular hydrogen bonding is effective.