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一般有机化学实验室,常要进行物质沸点的测定,进行蒸馏、分馏以及减压、加压等操作,这些实验,受大气压强的影响比较显著,应注意校正。沸点的测定,同一液体物质,在不同海拔(大气压强不同)的实验室,可测得不同的沸点。例如丙酮,在标准状态下,沸点为56.2℃,而在兰州市(海拔1500m)。大气压为634mmHg柱高时,实测其沸点为51.5℃。作为一物理常数,显然必须加以校正。在大气压改变不太大的范围内,许多液体物质的沸点随大气压的变化有近似的线性关系,并且有相近的斜率。
General organic chemistry laboratories, often for the determination of the material boiling point, distillation, fractionation and decompression, pressure and other operations, these experiments, the impact of atmospheric pressure is more significant, should pay attention to the correction. Determination of the boiling point, the same liquid material, at different altitudes (atmospheric pressure different) laboratory, can measure different boiling point. Such as acetone, in the standard state, the boiling point of 56.2 ℃, while in Lanzhou City (1500m above sea level). Atmospheric pressure of 634mmHg column height, the measured boiling point of 51.5 ℃. As a physical constant, obviously it must be corrected. In the range where the atmospheric pressure does not change much, the boiling points of many liquid substances have approximate linear relationship with the change of atmospheric pressure, and have similar slopes.