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So I have a multistep reaction

\begin{align} \ce{4 NH3 + 5 O2 &-> 4 NO + 6 H2O}\\ \ce{2 NO + O2 &-> 2 NO2}\\ \ce{3 NO2 + H2O &-> 2 HNO3 + NO} \end{align}

If I know the initial decreasing rate of $\ce{O2}$ and want to find the initial overall reaction rate, can I just look at the coefficient in the rate-determining step or do I need to consider $\ce{O2}$ in the other step too?

Also if I want average rate over a period of time, is it still the same?

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    $\begingroup$ As neither of these reactions is elementary, you need to determine the reaction rate order or more generally reaction rate equation for each of them first. Then you may try to determine the rate determining step. I am afraid this cannot be solved without much experimental data. // Additionally, I assume there reaction are not ongoing simultaneously in the same place, but sequentially at different conditions. $\endgroup$
    – Poutnik
    Commented Jun 26, 2023 at 8:32
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    $\begingroup$ Chem+Math Expression formatting reference: MathJax Basics / Chem+Math expressions/formulas/equations / Upright vs italic / Math SE Mathjax tutorial // MathJax is preferred not to be used in CH SE Q titles. $\endgroup$
    – Poutnik
    Commented Jun 26, 2023 at 12:18
  • $\begingroup$ The rate determining step approximation is not going to help here. You have in this short and incomplete sequence already two reactions giving a common product. $\endgroup$
    – Martin - マーチン ♦
    Commented Jun 26, 2023 at 21:25

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