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设计一种测量液-液体系混合时过量体积的装置-双支管膨胀计,能够测出十万分之几毫升的体积变化。在298.15K测量了苯-环己烷体系的过量体积,与代表性的文献数据满意相符。测量精确度为±0.0015cm~3mol~(-1)。利用上述装置,直接测量了苯-甲醇体系18个组分比时的混合体积变化(298.15K),得到V~E由正值转变为负值所对应的X_1(甲醇)约为 0.55,在Scatchard数据(0.5)与Washburn数据(0.6)之间。注意到甲醇吸收痕量水分后会使V~E值普遍升高。此外,试测了盐类(如碘化钾)对苯-甲醇体系过量体积的影响,发现正的V~E值升高,负的V~E值下降。
A volumetric device to measure the excess volume of the liquid-liquid system, a double-tube dilatometer, was designed to measure volume changes in the tens of thousands of milliliters. The excess volume of the benzene-cyclohexane system was measured at 298.15 K, which is in good agreement with the representative literature data. Measurement accuracy of ± 0.0015cm ~ 3mol ~ (-1). Using the above-mentioned apparatus, the change of the mixed volume of the benzene-methanol system (298.15K) was directly measured, and the X_1 (methanol) corresponding to the change of the V_E from positive to negative was about 0.55. Between data (0.5) and Washburn data (0.6). Note that trace amounts of methanol can cause the V to E values to increase generally. In addition, the effects of salts (such as potassium iodide) on the excess volume of the benzene-methanol system were tested and found that positive V-E values increased and negative V-E values decreased.