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双液系气液平衡相图实验是我国各类高等院校物理化学实验大纲规定的实验,在国外不少学校的物理化学实验中至今也广泛选用。此实验普遍采用的装置是双液系气液平衡沸点仪。可是,沸点仪上蒸气支管的位置和温度计水银球的位置,在国内外的教材中各不相同,对实验精度产生了影响。我们对双液系平衡相图实验进行了剖析,认为实验的关键是要能准确测定以蒸气支管口处为代表的气相和以瓶内液相两相平衡的温度以及从蒸气冷凝下来的溶液要能代表两相平衡的气相组成,条件实验表明:当温度计水银球全部浸入液相时,由于过热现象的存在,测得的温度往往较蒸气支管处的气相的温度高0.5℃右左,在克服暴沸不良时,甚至高出1.5℃,当温度计水银球一半浸入液相,另一半露于气相,或将温度计水银球三分之二置于溶液,三分之一留于气相时,由于沸腾时不可避免的溶液波动,实际
The double-liquid-phase gas-liquid equilibrium phase diagram experiment is an experiment stipulated in the physical chemistry experiment outline for all kinds of institutions of higher learning in our country. So far, a large number of physicochemical experiments in many foreign countries have been widely used. This experiment commonly used device is a two-liquid air-liquid equilibrium boiling point instrument. However, the position of the steam branch pipe on the boiling point meter and the position of the mercury ball of the thermometer are different in the teaching materials at home and abroad, which have an impact on the experimental accuracy. We analyzed the experiment of two-liquid balance phase diagram. The key point of the experiment is that we can accurately measure the gas phase represented by the steam branch nozzle and the solution which is balanced with the two phases of the liquid phase in the bottle and the solution condensed from the vapor Can represent the two phase equilibrium gas phase composition. The experimental results show that: when the thermometer mercury ball all immersed in the liquid phase, due to the existence of overheating, the measured temperature is often higher than the temperature of the vapor branch at the vapor phase temperature of about 0.5 ℃, Poor boiling, even higher than 1.5 ℃, when the thermometer mercury ball half immersed in the liquid phase, the other half exposed to the gas phase, or two-thirds of the thermometer mercury ball placed in solution, one-third left in the gas phase, due to boiling Inevitable solution fluctuations, the actual