运用盖斯定律可计算一些不易测定的反应的反应热.(1)已知在298K时下述反应的有关数据:C(s)+12O2(g

2025-06-25 15:04:29
推荐回答(1个)
回答1:

(1)已知:①、C(s)+

1
2
O2(g)=CO(g)△H1=-110.5kJ?mol-1
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