###### deepak kumar singh AskiitiansExpert-IITM

Last Activity: 14 Years ago

dear shamshad reyaz

first of all remember one thing about the order of reaction: order of reaction is a practically measured value, one can not determine it just by the reaction's equation, but still thr ways to determine the order of reaction.

In chemical kinetics, the **order of reaction** with respect to a certain reactant, is defined as thepower to which its concentration term in the rate law or rate equation is raised.

For example, given a chemical reaction 2A + B → C with a rate equation* : r* = *k*[A]^{α}[B]^{β }

the reaction **order with respect to** A would be **α** and with respect to B would be **β**, the **total reaction order** would be **α+****β**. It is not necessary that the order of a reaction be a whole number – zero and fractional values of order are possible. Reaction orders can be determined only by experiment. Their knowledge allows conclusions about the reaction mechanism.

The reaction order is *not necessarily* related to the stoichiometry of the reaction, unless the reaction is elementary. Complex reactions may or may not have reaction orders equal to their stoichiometric coefficients.

----->supoose if above reaction would be elementay then the order with repect to A and B would be 2 and 1 repectively and overall ordr of reaction would be 2+1=3.

------>suppose if a question provide you some experimental data about the concentration of reactant , then you have to put those values in the rate equation and find out the valuse of **α **and **β**.

-------> another approach to calculate the order of reaction by the unit of rate constant "**k**".

**unit of rate constant (k) = mol**^{1-n}·L^{n-1}·s^{-1 }

where n is the order of reaction.

but as i think the best way to calculate the order of reaction is to first of all understand the concept behind the order of reaction after that just appy that concept and you will youself find out the way to determine the order.

after all of this there are so many methods to determine the value of order of reaction.

so first of all read the concept and after that if you have some problem you can ask us.

Please feel free to post as many doubts on our discussion forum as you can. We are all IITians and here to help you in your IIT JEE preparation.

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**regard**

**Deepak kumar singh**

**B.TECH IIT madras**