化学反应热实验的过程分析及焓变计算

Analysis on the process and computation of enthalpy increment in chemical reaction heat experiment

高中化学教师教学用书以乙烷裂解为乙烯和氢气为例,估算化学反应热。但键能数据的来源很有限,而物质的焓资料较丰富易得,况且,化学反应中常伴随有诸如气体解吸、盐的溶解等物理变化过程,因此,用求反应系统的焓变来计算化学反应热,则较为容易且周详。这里,用焓变计算了乙烷高温裂解的反应热。并以高中化学第一册[实验1-4]为例做过程分析及焓变计算,从计算结果可知,该化学反应实验的吸热量很大,而且主要来自反应时氢氧化钡晶粉脱弃结晶水所引起的强烈吸热。

Applying enthalpy date to the computation of chemical reaction heat will be much more convenient and comprehensive if date of bond energy is used. The article analyses the process in the experiment（ experiment1-4, book one） in high school chemistry and computation of enthalpy increment based on the experiment. The result illustrates that chemical reaction in the experiment is a strong heat-absorbing reaction. Moreover, the heat results primarily from the strong heat absorption caused from the barium hydroxide abandons crystal water in the reaction.