(1)①CH4(g)+4NO2(g)═4NO(g)+CO2(g)+2H2O(g)△H=-574kJ/mol,
②CH4(g)+4NO(g)═2N2(g)+CO2(g)+2H2O(g)△H=-1160kJ/mol,
依据盖斯定律
得到CH4(g)+2NO2(g)=N2(g)+CO2(g)+2H2O(g)△H=-867 kJ/mol,①+② 2
故答案为:CH4(g)+2NO2(g)=N2(g)+CO2(g)+2H2O(g)△H=-867 kJ/mol;
(2)2NH3(g)+NO(g)+NO2(g)
2N2(g)+3H2O(g)△H<0,反应是气体体积增大的放热反应,依据化学平衡移动原理分析,增大氨气浓度,减小压强,降低温度;180℃ 催化剂
故答案为:增大NH3浓度(或减小压强、降低温度).