1、高考重要填空逐空特训(一)盖斯定律应用、反应热计算特训1已知：CH3OH、H2的燃烧热(H)分别为726.5 kJmol1、285.8 kJmol1，则常温下CO2和H2反应生成CH3OH和H2O的热化学方程式是_。答案CO2(g)3H2(g)=CH3OH(l)H2O(l)H130.9 kJmol1解析燃烧热是指1 mol可燃物完全燃烧生成稳定的氧化物时放出的热量。已知：CH3OH、H2的燃烧热(H)分别为726.5 kJmol1、285.8 kJmol1，则有：CH3OH(l)O2(g)=CO2(g)2H2O(l)H726.5 kJmol1，H2(g)O2(g)=H2O(l)H285.8 k
2、Jmol1，根据盖斯定律：3得常温下CO2和H2反应生成CH3OH和H2O的热化学方程式：CO2(g)3H2(g)=CH3OH(l)H2O(l)H130.9 kJmol1。2红磷P(s)和Cl2(g)发生反应生成PCl3(g)、PCl5(g)，反应过程如下：2P(s) 3Cl2(g) = 2PCl3(g)H612 kJmol12P(s) 5Cl2(g) =2PCl5(g)H798 kJmol1气态 PCl5生成气态PCl3和Cl2的热化学方程式为_。答案PCl5(g)PCl3(g) Cl2(g)H93 kJmol1解析已知：2P(s)3Cl2(g)=2PCl3(g)H612 kJmol1，2P
3、(s)5Cl2=2PCl5(g)H798 kJmol1，根据盖斯定律可知()/2即得到气态PCl5生成气态PCl3和Cl2的热化学方程式：PCl5(g)PCl3(g)Cl2(g)H93 kJmol1。3已知：2CH4(g)O2(g)=2CO(g)4H2(g)Ha kJmol1CO(g)2H2(g)=CH3OH(g)H b kJmol1试写出由CH4和O2制取气态甲醇的热化学方程式：_。答案2CH4(g)O2(g)=2CH3OH(g)H(a2b) kJmol1解析将给出的反应分别标为、，根据盖斯定律，把2可得CH4和O2制取甲醇的热化学方程式：2CH4(g)O2(g)=2CH3OH(g)H(a2
4、b) kJmol1。4已知：2Cu2S(s)3O2 (g)=2Cu2O(s)2SO2(g)H768.2 kJmol1 2Cu2O(s)Cu2S (s)=6Cu(s)SO2(g)H116.0 kJmol1 则Cu2S(s)O2 (g)=2Cu(s)SO2(g)H_。答案217.4 kJmol1解析根据盖斯定律，将方程式()得Cu2S(s)O2(g)=2Cu(s)SO2(g)H(768.2116.0) kJmol1217.4 kJmol1。5已知：N2(g)2O2(g)=2NO2(g)Ha kJmol1N2H4(g)O2(g)=N2(g)2H2O(g)Hb kJmol12NO2(g)N2O4(g)
5、Hc kJmol1写出气态肼在气态 N2O4 中燃烧生成氮气和气态水的热化学方程式_。答案2N2H4(g)N2O4(g)=3N2(g)4H2O(g)H (ac2b) kJmol1解析N2(g)2O2(g)=2NO2(g)，N2H4(g)O2(g)=N2(g)2H2O(g)，2NO2(g) N2O4(g)，2得出：2N2H4(g)N2O4(g)=3N2(g)4H2O(g)H(c2ba) kJmol1。6已知反应： 2SO2(g)O2(g)2SO3(g)H196.6 kJmol1 反应： 2NO(g)O2(g)2NO2(g)H113.0 kJmol1则SO2(g)与NO2(g)反应生成SO3(g)
6、和NO(g)的热反应方程式为_。答案SO2(g)NO2(g)SO3(g)NO(g)H41.8 kJmol1解析已知反应： 2SO2(g)O2(g)2SO3(g)H196.6 kJmol1，反应： 2NO(g)O2(g)2NO2(g) H113.0 kJmol1，根据盖斯定律()/2即得到SO2(g)与NO2(g)反应生成SO3(g)和NO(g)的热反应方程式：SO2(g)NO2(g)SO3(g)NO(g)H41.8 kJmol1。7已知：H2的热值为142.9 kJg1(热值是表示单位质量的燃料完全燃烧生成稳定的化合物时所放出的热量)；N2(g)2O2(g)=2NO2(g)H133 kJmol
7、1H2O(g)=H2O(l)H44 kJmol1催化剂存在下，H2还原NO2生成水蒸气和其他无毒物质的热化学方程式：_。答案4H2(g) 2NO2(g)=N2(g) 4H2O(g)H 1 100.2 kJmol1解析已知：H2的热值为142.9 kJg1，则 H2(g)O2(g)=H2O(l)H1285.8 kJmol1；N2(g)2O2(g)=2NO2(g)H2133 kJmol1；H2O(g)=H2O(l)H344 kJmol1；根据盖斯定律由44可得4H2(g)2NO2(g)=4H2O(g)N2(g)H(285.8 kJmol1)4(133 kJmol1)(44 kJmol1)41 10
8、0.2 kJmol1，故此反应的热化学方程式为 4H2(g)2NO2(g)=N2(g)4H2O(g)H1 100.2 kJmol1。8已知键能：NN 945 kJmol1，HH 436 kJmol1，NH 391 kJmol1。则氮气、氢气合成氨的热化学方程式是_。答案 N2(g) 3H2(g)2NH3(g)H 93 kJmol1解析已知键能：NN 945 kJmol1，HH 436 kJmol1，NH 391 kJmol1，则N2(g)3H2(g)2NH3(g)H(945 kJmol13436 kJmol1)(6391 kJmol1)93 kJmol1，故氮气、氢气合成氨的热化学方程式是N2(g)3H2(g)2NH3(g)H93 kJmol1。9H124 kJmol1部分化学键的键能如下表所示：化学键CHCCC=CHH键能/ kJmol1412348X436根据上述反应的能量变化，计算X_。答案612解析反应热反应物总键能生成物总键能，由有机物的结构可知，应是CH2CH3中总键能与CH=CH2、H2总键能之差，设C=C键能为X kJmol1，则H(54123483412X436) kJmol1124 kJmol1，解得X612。