(1)已知:①、C(s)+
O2(g)=CO(g)△H1=-110.5kJ?mol-1,1 2
②、C(s)+O2(g)=CO2(g)△H2=-393.5kJ?mol-1,
由盖斯定律,①×2-②得C(s)+CO2(g)=2CO(g),故该反应的△H=2×(-110.5kJ?mol-1)-(-393.5kJ?mol-1)=+172.5kJ?mol-1,
故答案为:+172.5kJ?mol-1;
(2)已知:③、N2(g)+2O2(g)=2NO2(g)△H=+67.7kJ?mol-l;
④、N2H4(g)+O2(g)=N2(g)+2H2O(g)△H=-534kJ?mol-l;
由盖斯定律,④×2-③得2N2H4(g)+2NO2(g)=3N2(g)+4H2O(g),故该反应的△H=2×(-534kJ?mol-1)-67.7kJ?mol-1)=-1135.7 kJ?mol-1,
即2N2H4(g)+2NO2(g)=3N2(g)+4H2O(g)△H=-1135.7 kJ?mol-1,
故答案为:2N2H4(g)+2NO2(g)=3N2(g)+4H2O(g)△H=-1135.7 kJ?mol-1.