(1)①H2(g)+
O2(g)═H2O(g)△H11 2
②N2(g)+2O2═2NO2(g)△H2
③
N2(g)+1 2
H2(g)═NH3(g)△H33 2
利用上述三个反应,结合盖斯定律计算①×6+2×②-4×③得到:4NH3(g)+7O2(g)═4NO2(g)+6H2O(g)的反应焓变为6△H1+2△H2-4△H3 ;
故答案为:6△H1+2△H2-4△H3 ;
(2)①CH4(g)+H2O(g)═CO(g)+3H2(g)△H=+206.2kJ?mol-1
②CH4(g)+CO2(g)═2CO(g)+2H2(g)△H=+247.4kJ?mol-1
结合盖斯定律①×2-②得到CH4(g)与H2O(g)反应生成CO2(g)和H2(g)的热化学方程式为:CH4(g)+2H2O(g)═CO2(g)+4H2(g)△H=+165.0 kJ?mol-1;
故答案为:CH4(g)+2H2O(g)═CO2(g)+4H2(g)△H=+165.0 kJ?mol-1;