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纯液体饱和蒸气压的测定是物理化学实验中的一个常规实验,通常用等压计法测定。在一定条件下,这种方法能得到满意结果,但在学生实验中往往误差较大,有时甚至失败。分析原因,我们认为主要是温度不平衡造成,抽气沸腾时液体气化带走气化热使自身温度降低,由于玻璃传热不良,被测液体又处于静止状态,液体和水温度达到平浴衡需要较长时间。如果实验中频繁抽气沸腾,平衡时间不足,盲目地以水温度代替体浴系温度,所得结果将误差甚大。我们用图<1>的装置摸拟等压计的条件,发现短时间抽气沸腾后即有3度多的温差(稍长时间可达10度以上)平衡10分钟后仍有明显的温差。因此严格操作时比较费时,测量点不易作多。测量体系也有一定的限制
Determination of pure liquid saturated vapor pressure is a routine experiment in physical chemistry experiments, usually measured by the isobaric meter method. Under certain conditions, this method can get satisfactory results, but the error in student experiments is often larger and sometimes fails. Analysis of the reasons, we believe that the main cause of the temperature imbalance caused by gasification vaporized vaporization of vaporization to lower its own temperature, due to poor heat transfer of glass, the measured liquid is at rest, the liquid and water temperature reaches the flat bath It takes a long time. If the experiment frequent pumping boiling, lack of balance time, the blind to the water temperature instead of bath temperature, the results will be very large error. We use Figure <1> device to simulate the conditions of isobaric meter and found that after a short time aspiration boiling three degrees more than the temperature difference (a little longer up to 10 degrees) balance after 10 minutes there are still significant temperature difference. Therefore, more time-consuming rigorous operation, the measurement point is not easy to make more. Measurement system also has some restrictions