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本文应用振动管式密度计,测定了278.15—318.15K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。
In this paper, the vibrational tube densitometer was used to determine the density of the DMF-H 2 solution with composition changes at 10 temperatures in the range of 278.15-318.15 K. The excess volume VE of the solution was calculated from the density values; The apparent molar volume φv and the partial molar volume V_ (DMF) of DMF under the composition and the regularity of VE, φv and V_ (DMF) with composition changes were found. The changes of DMF with x_ (DMF) The entropy of entropy transfer of DMF-H_2O solution is corresponding to the change rule. Both of them have extreme values at x_ (DMF) ≈0.075, so the liquid structure of DMF-H_2O is further discussed. DMF molecule may be embedded in molecular cage composed of 12 water molecules, thus forming the most compact structure.