Which property of water makes it the 'universal solvent'?

• A. It is a polar molecule
• B. It is nonpolar
• C. It has a low boiling point
• D. It forms hydrogen bonds only at high temps

Answer: (A)

Water is able to act as a universal solvent because it is a polar molecule. The unequal distribution of charge gives water a partial positive charge on the hydrogens and a partial negative charge on the oxygen, so it can interact strongly with charged ions and other polar molecules. When something like salt is added, water molecules surround the individual ions (hydration), pulling Na+ and Cl− apart and keeping them dissolved. Polar substances dissolve through similar dipole interactions and hydrogen bonding with water. Nonpolar substances don’t interact well with water, so they don’t dissolve easily. The fact that water forms hydrogen bonds isn’t limited to high temperatures and is part of why it dissolves so many substances in the first place.