Arun
Last Activity: 6 Years ago
A second-order reaction depends on the concentrations of one second-order reactant, or two first-order reactants.
For a second order reaction, its reaction rate is given by:
![\ -\frac{d[A]}{dt} = 2k[B]^2](http://upload.wikimedia.org/math/7/8/1/781cda9b25d2e92fb50c2f6a30188f41.png)
or
![\ -\frac{d[A]}{dt} = k[A][B]](http://upload.wikimedia.org/math/c/f/d/cfd5938b3763344a202d6975a0d68ed9.png)
or
In several popular kinetics books, the definition of the rate law for second-order reactions is
. Conflating the 2 inside the constant for the first, derivative, form will only make it required in the second, integrated form (presented below). The option of keeping the 2 out of the constant in the derivative form is considered more correct, as it is almost always used in peer-reviewed literature, tables of rate constants, and simulation software.[8]
The integrated second-order rate laws are respectively
or
[A]0 and [B]0 must be different to obtain that integrated equation.
The half-life equation for a second-order reaction dependent on one second-order reactant is
. For a second-order reaction half-lives progressively double.
Another way to present the above rate laws is to take the log of both sides: ![\ln{}r = \ln{}k + 2\ln\left[A\right]](http://upload.wikimedia.org/math/c/f/0/cf04309d2e7d76fc386ebfcf6877723f.png)
Examples of a Second-order reaction
Regards
Arun