Question

The unit of second order reaction rate constant is:

• A. $L^{-1} .$ mol. $s^{-1}$
• B. $ L^{2}.\,mol^{-2}.\,s^{-1} $
• C. $ L.\,mol.\,s^{-1} $ .
• D. $ s^{-1} $

Answer 1

Answer: (C)

$ L \,mol^{-1}\,s^{-1} $
According to second order reaction
$ 2A\rightarrow$ Product
rate of reaction $ -\frac{d[A]}{dt}\propto [A]^{2} $
or $ \frac{dA}{dt}=k[A]^{2} $
$ k= $
Reaction rate constant then unit of second order reaction rate constant
$ k=-\frac{d[A]}{dt}\times \frac{1}{[A]^{2}} $
$ =\frac{1}{s.mol\,L^{-1}} $ or
$ L\,mol^{-1}s^{-1} $