How do i know the order of the reaction? [closed]








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$$\ce{2N2O5 ↔ 2N2O4 + O2}$$ is this reaction first order or second order ? And why ?
I know first order is when duplicating the concetration the velocity duplicates too, and secod order reaction is of order n if, when doubling the concentration, the speed increase by $\pu{2^n}$. For this cases i need the velocitys and concentrations but i only have the initial concetration and 5 hal life times


[![Temperature x half life time](https://i.stack.imgur.com/i4eSi.png)](https://i.stack.imgur.com/i4eSi.png)
$$\ce{N2O5}= 2,4 mols\_0$$
I dont know what to do, cuz to know, would have to have this data . Am i wrong ?




Order is an experimental data. It is never possible to derive the order of a reaction from its chemical equation. The order has to be determined by measuring the rate of a chemical reaction (in $\pu{mol/s}$, or in $\pu{mol L^{-1} s^{-1}}$) , and plotting a function of this rate vs. time. If the logarithm of the rate decreases linearly with time, the order is $1$. If the reciprocal of the rate increases linearly with time, the order is $2$. This is not dependent on the chemical equation of the reaction. In both cases, the slope of the line is the rate constant, $\pu{k\_{1}}$ or $\pu{k\_{2}}$.


This is what you should have to do with your experimental results about the decomposition of $\ce{N2O5}$. But here all you know about this reaction is its half-life. And this parameter (half-life) is a characteristics and a constant of the first-order reactions. So from this very property, you can state that the reaction is first order, without doing any calculations.


As the half-life is known at different temperatures, it probably means that, in a second time, you would have to calculate the activation energy of the reaction.


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