马尿酸及乙酰苯胺燃烧能的测定

Combustion Energies of Hippuric Acid and Acetanilide

设计并建立一台精密转动弹热量计 ,能在恒温和绝热两种模式下操作 .测量数据的采集由在线微机自动完成 ,测量结果通过适当的程序计算 .用量热标准物质 NBS39i苯甲酸标定其能当量 ,偏差约为± 0 .0 0 6 % .马尿酸及乙酰苯胺的燃烧能测定值分别为 -( 2 35 4 2 .7± 0 .9) J/g和 -( 31 2 4 5 .8± 2 .4 ) J/g(平均值和标准偏差 ) .不确定度为总标准偏差的 2倍 ,分别为± 4 .5 J/g和± 7.5 J/g.结果与推荐值一致 .还讨论了这两个化合物作为低含氮量量热参考物质的性质 .

A new precision rotating-bomb calorimeter has been built. It can be operated in the isoperibol or in the adiabatic mode. The data of the measured temperature could be collected automatically by a microcomputer and the result of determination could be calculated by using appropriate software. In the isoperibol mode, the apparatus was calibrated by using NBS39i benzoic acid with a standard deviation of the mean of ±0.006%. The combustion energies of hippuric acid and acetanilide have been determined to be \{-(23 542.7±\}0.9) J/g and -(31 245.8±2.4) J/g(mean and its standard deviation) respectively. The uncertainties of these results were estimated as twice the overall standard deviation of mean, to be ±4.5 J/g and ±7.5 J/g, respectively. These results are in agreement with the recommended values. The properties of the two compounds as the reference materials for combustion calorimetry concerning compounds containing C, H, O and N with a low nitrogen content have been discussed.