| 释义 |
endothermic, a. Chem.|ɛndəʊˈθɜːmɪk|
[ad. F. endothermique (M. Berthelot Essai de mécanique chimique (1879) II. iv. ii. 18), f. endo- + thermic a.]
Characterized by, or attended with, the absorption of heat.
1884M. M. P. Muir Princ. Chem. i. iv. 254 To found a system of classification on the difference between exothermic and endothermic changes. 1890Bloxam's Chem. (ed. 7) 141 When C is burnt into CO2 by 2 N2O, it evolves 40,400 more units of heat than when burnt in O2, showing that, contrary to the usual law, heat is evolved in the decomposition of the N2O, amounting to 20,200 units per molecule. Such a compound is said to be endothermic. 1898Nature 18 Aug. 375 The true chemical equivalent of light energy can only be measured by means of an endothermic irreversible reaction. 1902Encycl. Brit. XXV. 37/1 Such endothermic bodies are nearly always found to show considerable violence in their decomposition. 1927Jrnl. Iron & Steel Inst. CXVI. 479 Practically all clays undergo an endothermic reaction between 100° and 650°C. 1945Electronic Engin. XVII. 670 The individual process of induced transformation is just as likely to be endothermic as exothermic. 1960New Biol. XXXI. 62 The formation is analogous to an endothermic compound or to any molecule in which energy is stored. 1963Higham Handbk. Papermaking v. 109 In the case of the sulphate process the reaction given above is endothermic and, as such, requires considerable heat to achieve completion. 1965New Scientist 4 Nov. 345/1 Beyond Mach 5 the heat to be absorbed will be so great that it will be necessary to use ‘endothermic fuels’ which undergo chemical reactions which absorb heat.
Restrict Chem. to sense in Dict. and add: [1.] Also (of a compound), absorbing heat during its formation and liberating it during its decomposition.
2. Zool. Exercising partial or total control over body temperature by means of the internal generation of heat; warm-blooded. Cf. homœothermic a. Opp. ectothermic a.
1946,1961[see ectothermic a.]. 1972Sci. Amer. June 71/2 In another category are the endothermic animals, in which the heat that determines body temperature is derived largely from the animal's own energy metabolism. 1979Nature 12 Apr. 635/1 Many workers have proposed that dinosaurs were endothermic, as are all living mammals and birds, rather than ectothermic, as are all living reptiles. 1985[see *endotherm n. 1].
Hence ˌendotherˈmicity n., the degree to which a reaction is endothermic.
1965Phillips & Williams Inorg. Chem. I. x. 347 It was found to be a good approximation that the energy of activation was either very small or very close to the endothermicity of the reaction. 1988Nature 28 Apr. 798/1 The activation energies of the first two channels, 10a and 10b, are determined mainly by reaction endothermicities as the reverse reactions have near-zero activation energies. |