| 释义 |
Le Chatelier|lə ʃæˈtɛljeɪ|
[The name of Henry Le Chatelier (1850–1936), French chemist.]
a. Used attrib. with reference to a test for the soundness (freedom from expansion) of cement using a small hollow brass cylinder split longitudinally and having pointers close to the split which indicate the extent of any expansion that occurs when the cylinder is filled with cement.
1904Specification for Portland Cement (B.S.I.) 7 The cement shall be tested by the Le Chatelier method, and shall in no case show a greater expansion than 12 millimetres after 24 hours aeration and 6 millimetres after seven days aeration. The apparatus for conducting the Le Chatelier test..consists of a small split cylinder of brass. 1930Engineering 18 July 62/1 Dry clay when adsorbing water increased in bulk and exerted..sufficient pressure to spring open the Le Chatelier gauge about 1 lb. per square inch. 1963A. M. Neville Properties of Concrete i. 50 The Le Chatelier test detects unsoundness due to free lime only.
b. Used attrib. and in the possessive († and in conjunction with the name of K. Ferdinand Braun (1850–1918), German physicist) to designate a principle enunciated by Le Chatelier, which states that if a constraint (such as a change in pressure or temperature) be applied to any system in equilibrium, the equilibrium will shift in such a way as to tend to counteract the effect of the constraint.
1910Chem. Abstr. IV. 1600 (heading) New isomerization of benzopinacolins and Le Chatelier's law. 1911Ibid. V. 3361 The author gives the following as the usual statement of the Le Chatelier–Braun principle. 1922Proc. Amer. Acad. Arts & Sci. LVII. 25 The condition which must be satisfied in order that the Le Chatelier Principle may hold with regard to the effect of a change in the initial mass of one component, is that the addition of such component shall accelerate or retard the transformation (at equilibrium). 1943Thorpe's Dict. Appl. Chem. (ed. 4) VI. 229/1 It would be expected from the Le Chatelier–Braun principle of mobile equilibrium that increase of pressure would exert a retarding effect upon the rate of a uni⁓molecular reaction. 1954A. R. Bailey Text-bk. Metall. viii. 232 A reaction involving a gaseous reactant is favoured by increase in operating pressure, and one involving a gaseous product by decrease of pressure or by sweeping it away in a gas stream; these points also follow from Le Chatelier's Principle. 1961A. Holderness Inorg. & Physical Chem. xviii. 258 If the temperature of an equilibrium system..is lowered, Le Chatelier's Principle requires the equilibrium to shift so as to tend to raise the temperature again; that is, to evolve heat. 1973Jrnl. Chem. Education L. 124 Since stretching a rubber band is an exothermic process, Le Chatelier's principle predicts that heat applied to a stretched rubber band will contract it. |