In the reaction A+B to give C+D, how do you obtain the kinetic law?

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• Dr W
Lv 7
4 weeks ago

it will be of the from

.. rate = k * [A]^m * [B]^n

where m and n are determined experimentally.

• 4 weeks ago

Thanks for the efforts, but that's not what I mean, I meant the kinetic law, r= k *** (complicated expression where there are concentrations of A,B,C,D), I know it starts with rA=kCA, etc, but I cannot reach the final result.

• 4 weeks ago

You have to determine it experimentally. In each experiment, you vary the concentrations of A and B while measuring the rate of the reaction.

A good way to start is with equal concentrations. Then hold A constant at that equal concentration value and double B. Then, hold B constant at that equal concentration value and double A.

What you now need to do is look at how the concentration changes affect the rate. For example, if A is doubled (B is constant) and the fate doubles, then the reaction is first order in A. If the rate does not change, the reaction is zero order in A (meaning that A does not appear in the rate law).

This technique is called the method of initial rates. I have some solved examples here:

https://www.chemteam.info/Kinetics/WS-Kinetics-met...