例8 N2O5分解反应的历程如下:-|||-(i) _(2)(O)_(5)xlongequal [高温]({K)_(1)}N(O)_(2)+(N{O)_(3)}-|||-(ii) (N{O)_(2)}+N(O)_(3)xrightarrow ({K)_(2)}NO+(O)_(2)+N(O)_(2)-|||-(jii) +N(O)_(3)xrightarrow ({k)_(3)}2N(O)_(2)-|||-(1)当用O2的生成速率表示反应的速率时,试用稳态近似法证明:-|||-_(1)=dfrac ({k)_(1)(k)_(2)}({k)_(1)+2(k)_(2)}[ (N)_(2)(O)_(5)] -|||-(2)设反应(ii)为决速步,反应(i)为快平衡,用平衡假设写出反应的速-|||-率表示式r2。-|||-(3)在什么情况下, _(1)=(r)_(2)?