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vapor pressure

(Encyclopedia)vapor pressure, pressure exerted by a vapor that is in equilibrium with its liquid. A liquid standing in a sealed beaker is actually a dynamic system: some molecules of the liquid are evaporating to f...

pressure

(Encyclopedia)pressure, in mechanics, ratio of the force acting on a surface to the area of the surface; it is thus distinct from the total force acting on a surface. A force can be applied to and sustained by a si...

blood pressure

(Encyclopedia)blood pressure, force exerted by the blood upon the walls of the arteries. The pressure in the arteries originates in the pumping action of the heart, and pressure waves can be felt at the wrist and a...

pressure group

(Encyclopedia)pressure group, body, organized or unorganized, that actively seeks to promote its particular interests within a society by exerting pressure on public officials and agencies. Pressure groups direct t...

vaporization

(Encyclopedia)vaporization, change of a liquid or solid substance to a gas or vapor. There is fundamentally no difference between the terms gas and vapor, but gas is used commonly to describe a substance that appea...

cloud chamber

(Encyclopedia)cloud chamber, device used to detect elementary particles and other ionizing radiation. A cloud chamber consists essentially of a closed container filled with a supersaturated vapor, e.g., water in ai...

Raoult's law

(Encyclopedia)Raoult's law räo͞olzˈ [key] [for F. M. Raoult, a French physicist and chemist] states that the addition of solute to a liquid lessens the tendency for the liquid to become a solid or a gas, i.e., r...

high blood pressure

(Encyclopedia)high blood pressure: see hypertension. ...

pressure-treated wood

(Encyclopedia)pressure-treated wood, wood that has had a liquid preservative forced into it in order to protect against deterioration due to rot or insect attack. The most commonly used preservatives are chromated ...

Le Châtelier's principle

(Encyclopedia)Le Châtelier's principle, chemical principle that states that if a system in equilibrium is disturbed by changes in determining factors, such as temperature, pressure, and concentration of components...