ⅰ.N2(g)+O2(g)⇌2NO(g) △H=+180.5kJ·mol-1;
ⅱ.2NO(g)+O2(g)⇌2NO2(g) △H=-114.0kJ·mol-1;
ⅲ.2NO2(g)⇌N2O4(g) △H=-52.7kJ·mol-1。
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