题目内容
有3个热化方程式:H2(g)+1/2O2(g)=H2O(g);△H ="a" kJ/mol![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824114627937332.jpg)
H2(g)+1/2O2(g)=H2O(l);△H =bkJ/mol![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824114627937332.jpg)
2H2(g)+O2(g)=2H2O(l);△H =ckJ/mol![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824114627937332.jpg)
关于它们的下列表述正确的是( )![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824114627937332.jpg)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824114627937332.jpg)
H2(g)+1/2O2(g)=H2O(l);△H =bkJ/mol
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824114627937332.jpg)
2H2(g)+O2(g)=2H2O(l);△H =ckJ/mol
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824114627937332.jpg)
关于它们的下列表述正确的是( )
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824114627937332.jpg)
A.a+b=c |
B.1mol H2O由气态变为液态吸收(a-b)kJ热量![]() |
C.氢气的燃烧热为c/2 kJ![]() |
D.1molH2 O由液态变为气态吸收l c/2-al kJ热量 |
D
本题考查反应热的计算。将2式减去1式可得,H2O(g)=H2O(l);△H =(b-a)kJ/mol,则B错误;H2O由气态变为液态是放出热量,所以b-a<0,即b<a,从热化方程式中计量数和物质的状态可知,2b=c,则A错误;燃烧热是正值,所以氢气的燃烧热为-c/2 kJ,C错误;D项正确。
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