Chemistry of Everyday Substances

Why water dissolves almost everything: it is about shape, not any other property

Water's ability to dissolve a wider range of substances than almost any other common liquid comes down to one specific structural fact: its polar (dipolar) molecular structure. A water molecule's bent shape and the unequal sharing of electrons between its oxygen and hydrogen atoms give it a partially negative end (near the oxygen) and a partially positive end (near the hydrogens). That charge separation lets water molecules surround and pull apart ions and other polar molecules, breaking them away from each other and holding them in solution, which is the actual mechanism behind water's famous status as the "universal solvent".

The trap in this fact is the number of other true statements about water that sound like they could be the explanation but are not. Water does have an unusually high specific heat capacity, it is genuinely classified as an oxide of hydrogen, and it does have a relatively low boiling point compared to some other liquids, but none of these three real properties is the reason water dissolves so many substances. Only the polar structure does that specific job; the other properties explain different things about water entirely (its role in moderating temperature, its chemical classification, its phase behaviour).

Familiar consumer items and the chemicals inside them

A cluster of everyday consumer-product facts recurs in this space, each one a case of an ordinary item containing a chemical most people would not expect from its name or use.

Lipstick has repeatedly been found to contain trace amounts of lead as a contaminant in some formulations, a genuine and documented consumer-safety concern rather than a myth. Soft drinks have used brominated vegetable oil as an emulsifier, added specifically to keep citrus flavouring evenly and stably mixed through the drink rather than separating out. And monosodium glutamate (MSG), a well-known flavour enhancer, is widely used in Chinese fast food, the association is real and long-documented, whatever the popular controversy around MSG's safety, which is a separate question from whether the pairing itself is accurate.

The pattern worth remembering across all three: the correct exam answer is very often that an unexpected-sounding chemical-in-product association is genuinely true, not a myth to be dismissed, and questions built this way test whether a candidate defaults to scepticism about surprising facts rather than checking each one on its own merits.

Quick revision points

• Water's exceptional solvent power comes specifically from its polar (dipolar) molecular structure, not from its specific heat capacity, its classification as an oxide of hydrogen, or its boiling point, all of which are real properties of water but answer different questions.
• Lipstick: can contain trace lead as a contaminant. Soft drinks: some have used brominated vegetable oil as an emulsifier to keep flavouring mixed. Chinese fast food: commonly uses MSG as a flavour enhancer. All three chemical-item pairings are genuine, documented associations, not myths.