Question

某些化學(xué)鍵鍵能數(shù)據(jù)如下：

化學(xué)鍵	H—H	Cl—Cl	H—Cl
鍵能/ kJ·mol－1	436	243	431

 

則下列熱化學(xué)方程式不正確的是(　　)

A. H2(g)＋Cl2(g)=HCl(g) ΔH＝－91.5 kJ·mol－1

B．H2(g)＋Cl2(g)=2HCl(g)ΔH＝－183 kJ·mol－1

C. H2(g)＋Cl2(g)=HCl(g)ΔH＝＋91.5 kJ·mol－1

D．2HCl(g)=H2(g)＋Cl2(g)ΔH＝＋183 kJ·mol－1

 

Answer 1

C

【解析】ΔH＝反應(yīng)物的鍵能之和－生成物的鍵能之和，H2(g)＋Cl2(g)=HCl(g)的ΔH＝(436 kJ·mol－1＋243 kJ·mol－1)/2－431 kJ·mol－1＝－91.5 kJ·mol－1，所以，A項(xiàng)對(duì)，C項(xiàng)錯(cuò)；B項(xiàng)反應(yīng)的ΔH＝436 kJ·mol－1＋243 kJ·mol－1－2×431 kJ·mol－1＝－183 kJ·mol－1，對(duì)；D項(xiàng)反應(yīng)的ΔH＝2×431 kJ·mol－1－(436 kJ·mol－1＋243 kJ·mol－1)＝＋183 kJ·mol－1，對(duì)。