$A_2 $ $\rightleftharpoons$ $ A + A$ ....... (ઝડપી) ;
$A + B_2\rightarrow AB + B$ ..... (ધીમી) ;
$ A + B \rightarrow AB$ ...... (ઝડપી)
\(r = K[A] [B_2]\)
\(A_2 \rightleftharpoons A + A\)
\({K_{eq}}\, = \,\,\frac{{[A][A]}}{{[{A_2}]}}\)
\([A]\, = K_{eq}^{1/2}\,{[{A_2}]^{1/2}}\)
\(r= K \times \,K_{eq}^{1/2}{[{A_2}]^{1/2}}{[{B_2}]^1}\)