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化学反应过程中放出或吸收的热量叫做化学反应的反应热。
在恒温、恒压的条件下，化学反应过程中所吸收或释放的热量称为反应的焓变。其符号记为△H，单位为kJ/mol。规定吸热反应的焓变大于零，放热反应的焓变小于零。
下面的表格计算反应热焓为NO3 + H2O -----> HNO3 + OH文章源自公式库网-https://www.gongshiku.com/html/201910/huaxuefanyinghanbianshuzhizaixianjisuanyijianshengchengjisuanqi.html
请记住以下规则：文章源自公式库网-https://www.gongshiku.com/html/201910/huaxuefanyinghanbianshuzhizaixianjisuanyijianshengchengjisuanqi.html
热焓变化 自发反应？文章源自公式库网-https://www.gongshiku.com/html/201910/huaxuefanyinghanbianshuzhizaixianjisuanyijianshengchengjisuanqi.html
放热 (dH < 0) 是, dG < 0文章源自公式库网-https://www.gongshiku.com/html/201910/huaxuefanyinghanbianshuzhizaixianjisuanyijianshengchengjisuanqi.html
放热 (dH < 0) If |T dS| < |dH| 吸热 (dH > 0) If T dS > dH文章源自公式库网-https://www.gongshiku.com/html/201910/huaxuefanyinghanbianshuzhizaixianjisuanyijianshengchengjisuanqi.html
吸热 (dH > 0) No, dG > 0文章源自公式库网-https://www.gongshiku.com/html/201910/huaxuefanyinghanbianshuzhizaixianjisuanyijianshengchengjisuanqi.html
文章源自公式库网-https://www.gongshiku.com/html/201910/huaxuefanyinghanbianshuzhizaixianjisuanyijianshengchengjisuanqi.html 文章源自公式库网-https://www.gongshiku.com/html/201910/huaxuefanyinghanbianshuzhizaixianjisuanyijianshengchengjisuanqi.html
