At first glance, the number seems trivial. The density of pure (anhydrous) ethyl alcohol at room temperature (20°C / 68°F) is approximately . But don't let the "0.789" fool you. This tiny decimal point is a chemical rebel, and its behavior tells a fascinating story. The Rebel Who Floats Let’s start with the most obvious magic trick: density is why your "heavy" rocks sink and your "light" cork floats. Water has a density of 1.00 g/cm³. Ethanol, at 0.789, is significantly lighter.
The universe cheats. Because the molecules of water and alcohol love each other (thanks to hydrogen bonding), they pack together more tightly than they do with their own kind. The water molecules slip into the spaces between the ethanol molecules. alcohol etílico densidad
Ethyl alcohol expands with temperature much faster than water does. A hydrometer calibrated for 20°C will lie to you if you test a warm spirit at 30°C. It will read a lower alcohol content than what is actually present because the hot liquid has expanded, lowering its density. At first glance, the number seems trivial