物理化学学报 >> 1990, Vol. 6 >> Issue (02): 203-208.doi: 10.3866/PKU.WHXB19900214

研究论文 上一篇    下一篇

在278.15-318.15 K范围内DMF-H2O体系的超额摩尔体积及DMF的表观摩尔体积和偏摩尔体积的测定与研究

褚德萤; 张颖; 胡京诞; 刘瑞麟   

  1. 北京大学化学系
  • 收稿日期:1988-08-08 修回日期:1989-08-21 发布日期:1990-04-15
  • 通讯作者: 褚德萤

Excess Molar Volumes of Mixtures of N,N-Dimethylformamide and Water and Apparent Molal Volumes and Partial Molal Volumes of N,N-Dimethylformamide in Water From 278.15 K to 318.15 K

Chu De-Ying; Zhang Ying; Hu Jing-Dan; Liu Rui-Lin   

  1. Department of Chemistry, Peking University
  • Received:1988-08-08 Revised:1989-08-21 Published:1990-04-15
  • Contact: Chu De-Ying

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摘要： 本文应用振动管式密度计, 测定了278.15—318.15 K范围内10个温度下, DMF-H_2溶液的密度随组成的变化. 根据密度值求出溶液的超额体积VE; 在全部浓度的范围内不同组成下DMF的表观摩尔体积φv及偏摩尔体积V_(DMF); 及VE、φv和V_(DMF)随组成变化的规律. 发现V_(DMF)随x_(DMF)的变化与NaCl由水至DMF-H_2O溶液的转移熵有对应的变化规律, 均在x_(DMF)≈0.075处有极值, 从而进一步对DMF-H_2O的液体结构进行了讨论, 认为当x_(DMF)=0.075时, 单个DMF分子可能嵌入12个水分子组成的分子笼中, 从而形成最紧密结构。

Abstract: The densities of the mixtures of N,N-Dimethylformamide (DMF) and water(w) have been measured at ten temperatures from 278.15 K to 318.15 K with the vibra-tingtube density meter(Anton Paar Model DMA602). Then the excess molal volumes V~E of solutions and apparent and partial molal volumes of DMF over the range of mole fraction 0-1 have been determined. Comparing these quantities as functions of mole fraction of mixtures with the standard entropies of transfer for NaCl from water to DMF-H_2O mixtures as function of mole fraction of mixed solvent we found out there is a correspondence between the V_(DMF) varied with x and the standard entropies of transfer of NaCl. Both have the extremes at x=0.075. Therefore the structure of solution have been discussed. It might be considered that monomeric DMF molecules have been trapped in a quasi-clathrate "cage" made up of 12 water molecules at x=0.075 forming the possible closest packing of particles.