Question

【题目】已知：(1)H2(g) +1/2O2(g)＝H2O(g) △H＝-241.8 kJ/mol

(2)1/2N2 (g) + O2(g)＝NO2(g) △H＝＋33.9 kJ/mol

(3)1/2N2 (g) +3/2 H2(g)＝NH3(g) △H＝-46.0 kJ/mol

计算NH3(g)燃烧生成NO2(g)和H2O(g)的燃烧热

A．282.8 kJ/mol B．-282.8 kJ/mol C．848.4kJ/mol D．-848.4 kJ/mol

Answer 1

【答案】A

【解析】

试题分析：①H2(g)+O2(g)=H2O(g)△H1=-241.8kJmol-1，②N2(g)+O2(g)=NO2(g)△H2=+33.9kJmol-1，③N2(g)+H2(g)=NH3(g)△H3=-46.0kJmol-1，依据热化学方程式和盖斯定律计算①×+②-③得到NH3(g)燃烧生成NO2 (g)和H2O(g) 热化学方程式：NH3(g)+O2(g)=NO2(g)+H2O(g)△H=-282.8kJmol-1 ，故选A。