Question

【題目】肼(N2H4)是火箭發動機的燃料，它與N2O4反應生成氮氣和水蒸氣。已知：

①N2(g)＋2O2(g)===N2O4(g)ΔH＝＋8.7 kJ·mol－1

②N2H4(g)＋O2(g)===N2(g)＋2H2O(g)ΔH＝－534.0 kJ·mol－1

下列表示肼跟N2O4反應的熱化學方程式正確的是

A.2N2H4(g)＋N2O4(g)===3N2(g)＋4H2O(g) ΔH＝－542.7 kJ·mol－1

B.2N2H4(g)＋N2O4(g)===3N2(g)＋4H2O(g) ΔH＝－1 076.7 kJ·mol－1

C.N2H4(g)＋N2O4(g)=== N2(g)＋2H2O(g) ΔH＝－1 076.7 kJ·mol－1

D.2N2H4(g)＋N2O4(g)===3N2(g)＋4H2O(g) ΔH＝－1 059.3 kJ·mol－1

Answer 1

【答案】B

【解析】

肼(N2H4)是火箭發動機的燃料，它與N2O4反應生成氮氣和水蒸氣，已知：①N2(g)＋2O2(g)＝N2O4(g) ΔH＝＋8.7kJ·mol－1，②N2H4(g)＋O2(g)＝N2(g)＋2H2O(g) ΔH=－534.0kJ·mol－1，將方程式②×2-①得N2H4跟N2O4反應的熱化學方程式，2N2H4(g)＋N2O4(g)＝3N2(g)＋4H2O(g) ΔH=－1076.7kJ·mol－1或N2H4(g)＋N2O4(g)=N2(g)＋2H2O(g) ΔH=-538.35kJ·mol－1，B選項符合題意；

答案選B。