In physics, superheating (sometimes referred to as boiling delay) is the phenomenon in which a liquid is heated to a temperature higher than its standard boiling point, without actually boiling. This can be caused by rapidly heating a homogeneous substance while leaving it undisturbed (so as to avoid the introduction of air bubbles at nucleation sites).
Because a superheated fluid is the result of artificial circumstances, it is metastable, and is disrupted as soon as the circumstances abate, leading to the liquid boiling very suddenly and violently—a very dangerous situation. Superheating is sometimes a concern with microwave ovens, some of which can quickly heat water without physical disturbance. A person agitating a container full of superheated water by attempting to remove it from a microwave will likely be scalded.
The boiling point of a substance is the temperature at which it can change its state from a liquid to a gas throughout the bulk of the liquid.
Boiling on the other hand is a bulk process, so at the boiling point molecules anywhere in the liquid may be vaporized, resulting in the formation of vapor bubbles.
A somewhat clearer definition of boiling point is that it is the temperature at which the vapor pressure of the liquid equals the pressure of the environment.
Feeds |
Contact