CIESC Journal

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不挥发溶质对混合溶剂沸点及蒸气压的影响

孙仁义; 孙茜   

  1. 河南大学化学系; 华东师范大学化学系
  • 出版日期:2002-09-25 发布日期:2002-09-25

EFFECT OF NON-VOLATILE SOLUTES ON BOILING POINT AND VAPOR PRESSURE OF MIXED SOLVENT

SUN Renyi;SUN Qian   

  • Online:2002-09-25 Published:2002-09-25

摘要: 测定了若干不挥发溶质对醇 (甲醇、乙醇、正丙醇 ) -水双液系恒压 (100.3kPa)汽液平衡的影响 ,其中包括 16种不挥发溶质对正丙醇 -水恒沸混合物沸点的影响 .通过理论分析 ,得到少量不挥发溶质对具有固定组成的二元混合溶剂沸点及蒸气压影响的普遍性结论 :不挥发溶质使难挥发组分的气相组成增加是引起溶液蒸气压降低或沸点升高的充分条件 ;在恒沸混合物中无论不挥发溶质使气相组成发生何种变化都会引起溶液蒸气压降低或沸点升高 .经检验 ,该结论与实验结果及大量文献数据完全相符 .

Abstract: The effects of some non-volatile solutes on the boiling point of alcohol (methanol,ethanol,1-propanol)/water binary mixed solvent were determined by isobaric VLE experiments,with mixed solvent composition held constant.The effects of sixteen various non-volatile solutes on the boiling point of 1-propanol/water azeotrope were included.A strict thermodynamic equation on the effect of non-volatile solute on VLE of binary mixed solvent was derived.By means of theoretical analysis of the equation,two conclusions of universal significance were obtained:(1) when a little non-volatile solute dissolves in a binary mixed solvent with constant composition,boiling point will be elevated or vapor pressure will be depressed with increasing vapor composition of the less volatile component;(2) when a little non-volatile solute dissolves in azeotrope,any kind of solute always causes elevation of boiling point or depression of vapor pressure no matter how the vapor composition changes.The above conclusions were verified with the experiments of this paper and relevant experimental data in the literature,all of the experiment results were in agreement with the above conclusions without exception.