Why is water often called the universal solvent?

• A. Because it is nonpolar
• B. Because it is polar and can dissolve many substances
• C. Because it forms metallic bonds
• D. Because it is a gas

Answer: (B)

Water’s ability to act as a universal solvent comes from its polarity. Each molecule has a partial negative charge near the oxygen atom and partial positive charges near the hydrogens, creating a strong dipole. That polarity lets water attract and surround ions and polar molecules, forming hydration shells that separate solute particles and stabilize them in solution. When salts dissolve, water molecules surround the individual ions (like Na+ and Cl−), weakening the forces holding the solid together and pulling the ions into the solution. The same dipole interactions enable water to dissolve many polar covalent compounds and even some gases, making it capable of dissolving a wide variety of substances. Nonpolar substances don’t interact as well with water’s charged regions, so they don’t dissolve as readily. Water isn’t characterized by metallic bonds or by being a gas in its typical liquid solvent role, so those ideas don’t account for its solvent behavior. This combination of strong solvent–solute interactions driven by polarity is what makes water so versatile as a solvent.