critical temperature

critical temperature

[′krid·ə·kəl ′tem·prə·chər]

(agriculture)

The temperature below which a plant cannot grow.

(physical chemistry)

The temperature of the liquid-vapor critical point, that is, the temperature above which the substance has no liquid-vapor transition. Symbolized T_c.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

critical temperature

1. The temperature at which a steel structure cannot carry the service load for which it was designed because of softening of the steel that occurs when it is heated significantly.

2. Same as self-ignition temperature.

McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.

critical temperature

i. The temperature inside the cylinder of a reciprocating engine that will cause the fuel to explode rather than burn evenly when it is ignited.
ii. The temperature at which the internal structure of a metal takes on a crystalline form.

An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Critical Temperature

 

(1) The temperature of a substance in its critical state. For single substances the critical temperature is defined as the temperature at which the physical properties of the liquid and the vapor in equilibrium become identical. At the critical temperature the density of the saturated vapor and the liquid become identical, the interface between them disappears, and the heat of vaporization becomes zero. The critical temperature is one of the constants of a substance. (For the value of the critical temperature T_c for some substances, see.)

In binary systems (for example, propane-isopentane) the fluid-vapor equilibrium has no single critical temperature but rather a spatial critical curve for which the terminal points are the critical temperatures of the pure components.

(2) The temperature in fluid mixtures having components of limited solubility at which the mutual solubility becomes unlimited; it is called the critical solution temperature.

(3) The transition temperature of a number of conductors into the superconducting state. It has been measured for a large number of metals, alloys, and chemical compounds. In pure metals the lowest critical temperature occurs in titanium (0.37°K) and the highest in technetium (11.2°K). A very high value has been found in the compound Nb₃Ge (T_c ≈ 23°K).

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.