论文部分内容阅读
作者用分光光度计测定25℃下甲苯在十五种盐水溶液中的盐析常数k。所用的盐为:LiCl,NaCl,KCl,CsCl,NH_4Cl,NaF,NaBr,NaClO_3,NH_4Br,(CH_3)_4NBr,(C_2H_5)_4NBr,MgCl_2,CaCl_2,SrCl_2,BaCl_(20)在十五种盐中,只有两个溴化季铵盐对甲苯起盐溶作用,其余均起盐析作用。对于1—1价盐,k值的次序是NaF>NaCl>KCI>NaBr>NaClO_3>LiCl>NH_4Cl>CsCl>NH_4Br>(CH_3)_4NBr>(C_2H_5)_4NBr。这次序和一般非极性非电解质的盐析效应次序相同。定性地符合van der Waals力理论,Dcbye-McAulay的静电理论以及McDevit和Long的内压力理论。对于2—1价盐,k值的次序是BaCl_2>SrCl_2>CaCl_2>MgCl_(20)即盐析效应随离子晶体半径的增加而上升。这次序和色散力理论的次序恰相反。但是,如果假设二价离子对水的静电作用能伸展到原水化层以外的水分子,并考虑水化离子和水的静电作用,以及它和甲苯的色散作用,以上四种盐的反常次序就得到解释。
The author uses a spectrophotometer to determine the salting-out constant k of toluene at 15 ° C in 25 ° C. The salts used were LiCl, NaCl, KCl, CsCl, NH4Cl, NaF, NaBr, NaClO3, NH4Br, (CH3) 4NBr, (C2H5) 4NBr, MgCl2, CaCl2, SrCl2 and BaCl20. Only two brominated quaternary ammonium salts of toluene from the role of salt, salt precipitation from the rest role. For 1-1 salt, the order of k value is NaF> NaCl> KCI> NaBr> NaClO_3> LiCl> NH_4Cl> CsCl> NH_4Br> (CH_3) _4NBr> (C_2H_5) _4NBr. This order is the same as the salting-out effect of a non-polar non-electrolyte. Qualitatively fit the van der Waals force theory, Dcbye-McAulay’s electrostatic theory and McDevit and Long’s internal pressure theory. For 2-1 salts, the order of k value is BaCl_2> SrCl_2> CaCl_2> MgCl_ (20), that is, the salting-out effect increases with the increase of the ionic crystal radius. The order and dispersion theory are the opposite. However, if it is assumed that the electrostatic effect of divalent ions on water can extend to water molecules other than the original hydration layer and that the electrostatic action of hydrated ions and water, as well as its dispersion with toluene, is considered, the anomalous order of the above four salts Be explained.