A colorless fuming liquid formedby passing sulfur(Ⅳ) oxide over phos-phorus(Ⅴ) chloride and distilling themixture obtained. Sulfur dichloride oxideis used in organic chemistry to introducechlorine atoms (for example,into ethanolto form monochloroethane),t...[继续阅读]

    A member of a group oforganic compounds,general formulaR2C=CO,where R is hydrogen or an or-ganic radical. The simplest member is thecolorless gas ketene,CH2＝CO;the otherketenes are colored because of the presenceof the double bonds. Ketenes are unstablean...[继续阅读]

    A radioactive element of thealkali-metal group. It is found on Earthonly as a short-lived product of radioac-tive decay,occurring in uranium ores in mi-nute quantities. A large number of radioi-sotopes of francium are known.Symbol:Fr;m. p. 27℃;b. p.677℃;p...[继续阅读]

    A vapor that is in equi-librium with the solid or liquid. A saturat-ed vapor is at the maximum pressure (thesaturated vapor pressure) at a given tem-perature. If the temperature of a saturatedvapor is lowered,the vapor condenses.Under certain circumstance...[继续阅读]

    A salt of dithionic acid.连二硫酸的盐。...[继续阅读]

    See cyanoferrate.参阅cyanoferrate。...[继续阅读]

    The organicgroup,CH2＝CH—CH2—,derived by re-moving one hydrogen atom from propene. 有机基团CH2＝CH—CH2,是从丙烯除去一个氢原子而得到的。...[继续阅读]

    A derivative of the first law ofthermodynamics. It states that the totalheat change for a given chemical reactioninvolving alternative series of steps is inde-pendent of the route taken.热力学第一定律的衍生。它说明对一给定化学反应,涉及的每一步骤的总热能变化与所采取...[继续阅读]

    A technique used todetermine the structure of substances,principally the shapes of molecules in thegaseous phase. A beam of electrons direct-ed through a gas at low pressure produces aseries of concentric rings on a photographicplate. The dimensions of th...[继续阅读]

    A furnace for producing iron from iron(Ⅲ)oxide. A mixture of the orewith coke and a flux is heated by pre-heated air blown into the bottom of the fur-nace.The flux is often calcium oxide (fromlimestone).Molten pig iron is run off fromthe bottom of the fur...[继续阅读]