Scientists Are Still Learning New Things About Water
By LIDA TUNESI
Most students learn in grade school that water freezes at 32 degrees Fahrenheit, or zero degrees Celsius. Later, a student might go on to a chemistry class and learn that the freezing point actually depends on pressure, as well. From there, things only get more complicated.
In a new study, researchers showed that supercooled water can exist as two liquids with different densities.
“This is a fundamental finding that explains naturally many of the anomalous properties of water at low temperatures,” he told Brooklyn College.
Water, the so-called “universal solvent,” has many unique properties and responds to varying conditions differently than other substances. About 30 years ago, researchers predicted that water could exist in two forms—a high-density liquid and a low-density liquid—when cooled to extremely low temperatures. But since ice starts to form so quickly at these temps, these ideas have been hard to demonstrate.
The researchers used a combination of computer simulations and laboratory experiments to show this so-called “liquid-liquid transition” for the first time. They demonstrated that when you cool water to about 63 degrees below zero Celsius, two liquids of different densities form.
This process of cooling a substance below its freezing point without turning it into a solid is called “supercooling.” It is possible only when there is no “seed crystal” around which the rest of the solid build off and start to take shape.