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...[繼續(xù)閱讀]

    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...[繼續(xù)閱讀]

    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...[繼續(xù)閱讀]

    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...[繼續(xù)閱讀]

    A salt of dithionic acid.連二硫酸的鹽。...[繼續(xù)閱讀]

    See cyanoferrate.參閱cyanoferrate。...[繼續(xù)閱讀]

    The organicgroup,CH2＝CH—CH2—,derived by re-moving one hydrogen atom from propene. 有機(jī)基團(tuán)CH2＝CH—CH2,是從丙烯除去一個(gè)氫原子而得到的。...[繼續(xù)閱讀]

    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.熱力學(xué)第一定律的衍生。它說明對一給定化學(xué)反應(yīng),涉及的每一步驟的總熱能變化與所采取...[繼續(xù)閱讀]

    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...[繼續(xù)閱讀]

    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...[繼續(xù)閱讀]