critical point

1. Physics. the point at which a substance in one phase, as the liquid, has the same density, pressure, and temperature as in another phase, as the gaseous.2. Math.a. (of a function of a single variable) a point at which the derivative of the function is zero.b. (of a function of several variables) a point at which all partial derivatives of the function are zero.[187580]
* * *
In science, the set of conditions under which a liquid and its vapour become identical.The conditions are the critical temperature, the critical pressure, and the critical density. If a closed vessel is filled with a pure substance, partly liquid and partly vapour, and the average density equals the critical density, the critical conditions can be achieved. As the temperature is raised, the vapour pressure increases, and the gas phase becomes denser while the liquid expands and becomes less dense. At the critical point, the densities of liquid and vapour become equal, eliminating the boundary between the two.* * *
▪ phase changein physics, the set of conditions under which a liquid and its vapour become identical (see phase diagram). For each substance, the conditions defining the critical point are the critical temperature, the critical pressure, and the critical density.This is best understood by observing a simple experiment. If a closed vessel is filled with a pure substance, partly liquid and partly vapour, so that the average density equals the critical density, the critical conditions can be achieved. As the temperature is raised, the vapour pressure increases, and the gas phase becomes denser. The liquid expands and becomes less dense until, at the critical point, the densities of liquid and vapour become equal, eliminating the boundary between the two phases. If the average density at the start is too low, all the liquid will evaporate before the critical temperature is reached. If the initial average density is too high, the liquid will expand to fill the container.* * *
Universalium. 2010.
Look at other dictionaries:
Critical point — may refer to: Critical point (mathematics) Critical point (set theory) Critical point (thermodynamics) Construction point of a ski jumping hill See also Brillouin zone Percolation thresholds … Wikipedia
critical point — crit ic*al point (Physics), That combination of volume and pressure, at the critical temperature of the substance, at which the liquid and gaseous phases of a given quantity of a substance have identical values for their densities and other… … The Collaborative International Dictionary of English
critical point — index cornerstone, crossroad (turning point), emergency, main point Burton s Legal Thesaurus. William C. Burton. 2006 … Law dictionary
critical point — n. the physical condition, specified by pressure or density, at which a substance at its critical temperature can exist as a liquid and vapor in equilibrium … English World dictionary
Critical point — Critical point. См. Критическая точка. (Источник: «Металлы и сплавы. Справочник.» Под редакцией Ю.П. Солнцева; НПО Профессионал , НПО Мир и семья ; Санкт Петербург, 2003 г.) … Словарь металлургических терминов
critical point — The point between two bases from which it will take the same time to fly to either base. An aircraft flying at flight level 350 has pressurization failure and is forced to descend to flight level 130. At critical point, it can either proceed to… … Aviation dictionary
critical point — noun a crisis situation or point in time when a critical decision must be made at that juncture he had no idea what to do he must be made to realize that the company stands at a critical point • Syn: ↑juncture, ↑crossroads • Hypernyms: ↑crisis … Useful english dictionary
critical point — kritinis taškas statusas T sritis automatika atitikmenys: angl. critical point vok. kritischer Punkt, m rus. критическая точка, f pranc. point critique, m … Automatikos terminų žodynas
critical point — kritinis taškas statusas T sritis Standartizacija ir metrologija apibrėžtis Viensandės ar daugiasandės sistemos būsenos diagramos taškas, apibūdinamas kritinėmis temperatūros, slėgio, tūrio, tankio ir sudėties vertėmis. atitikmenys: angl.… … Penkiakalbis aiškinamasis metrologijos terminų žodynas
critical point — kritinis taškas statusas T sritis fizika atitikmenys: angl. critical point vok. kritischer Punkt, m rus. критическая точка, f pranc. point critique, m … Fizikos terminų žodynas