△H的四种计算方法
![](https://wkrtcs.bdimg.com/rtcs/image?w=245.33&md5sum=ea02dc8bfdefa4fb94df162060485852&sign=6ccf1c9112&rtcs_flag=1&rtcs_ver=4&l=webapp&bucketNum=535&ipr={"t":"img","r":"r_3","w":"245.33","h":"161.33","dataType":"gif","c":"word/media/image1.gif"})
1.化学方程式法
化学反应伴随物质变化 化学方程式 标明物质状态
能量变化 △H 热化学方程式 单位：kJ/mol
符号：+ —
系数表明物质的量
物质变化与能量变化成比例
例题：
![](https://wkrtcs.bdimg.com/rtcs/image?w=705.00&md5sum=ea02dc8bfdefa4fb94df162060485852&sign=6ccf1c9112&rtcs_flag=1&rtcs_ver=4&l=webapp&bucketNum=535&ipr={"t":"img","r":"r_11","w":"705.00","h":"71.00","dataType":"png","c":"word/media/image2.png","imgOriW":940,"imgOriH":74})
2.依据总能量（相对能量计算）
E
![](https://wkrtcs.bdimg.com/rtcs/image?w=120.00&md5sum=ea02dc8bfdefa4fb94df162060485852&sign=6ccf1c9112&rtcs_flag=1&rtcs_ver=4&l=webapp&bucketNum=535&ipr={"t":"img","r":"r_12","w":"120.00","h":"150.67","dataType":"gif","c":"word/media/image3.gif"})
生成物
△H
E1
E2 反应物
![](https://wkrtcs.bdimg.com/rtcs/image?w=158.67&md5sum=ea02dc8bfdefa4fb94df162060485852&sign=6ccf1c9112&rtcs_flag=1&rtcs_ver=4&l=webapp&bucketNum=535&ipr={"t":"img","r":"r_4","w":"158.67","h":"16.00","dataType":"gif","c":"word/media/image4.gif"})
反应进程 △H=E1-E2＞0 △H=生成物总能量—反应物总能量
相对能量
（4）一定条件下，在水溶液中1 mol Cl－、ClOx－（x= 1，2，3，4）的能量（KJ）相对大小如有图所示。
![](https://wkrtcs.bdimg.com/rtcs/image?w=246.00&md5sum=ea02dc8bfdefa4fb94df162060485852&sign=6ccf1c9112&rtcs_flag=1&rtcs_ver=4&l=webapp&bucketNum=535&ipr={"t":"img","r":"r_18","w":"246.00","h":"196.00","dataType":"png","c":"word/media/image5.png","imgOriW":282,"imgOriH":225})
B→A + C反应的热化学方程式为（用离子符号表示）。
![](https://wkrtcs.bdimg.com/rtcs/image?w=177.33&md5sum=ea02dc8bfdefa4fb94df162060485852&sign=6ccf1c9112&rtcs_flag=1&rtcs_ver=4&l=webapp&bucketNum=535&ipr={"t":"img","r":"r_4","w":"177.33","h":"125.33","dataType":"gif","c":"word/media/image6.gif"})
3.依据键能计算（注意对比能量）
E E1 反应物 放热反应为例 △H＞0 反应物吸收能量（断键）
△H E2 断键完成后新减生成放出热
生成物
反应进程 △H=E1-E2 反应物的键能总和—生物的键能总和
放热相同
例题
![](https://wkrtcs.bdimg.com/rtcs/image?w=705.00&md5sum=ea02dc8bfdefa4fb94df162060485852&sign=6ccf1c9112&rtcs_flag=1&rtcs_ver=4&l=webapp&bucketNum=535&ipr={"t":"img","r":"r_7","w":"705.00","h":"261.00","dataType":"png","c":"word/media/image7.png","imgOriW":968,"imgOriH":313})
2 注意方向和系数
![](https://wkrtcs.bdimg.com/rtcs/image?w=704.00&md5sum=ea02dc8bfdefa4fb94df162060485852&sign=6ccf1c9112&rtcs_flag=1&rtcs_ver=4&l=webapp&bucketNum=535&ipr={"t":"img","r":"r_9","w":"704.00","h":"242.00","dataType":"png","c":"word/media/image8.png","imgOriW":768,"imgOriH":290})
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