\(A\,+\,2B\,\longrightarrow\,C\)
Rate of reaction \(r=\frac{-d[A]}{dt}=\frac{-1}{2}\frac{d[B]}{dt}=\frac{d[C]}{dt}\)
\(R=K[A][B]^2\)
\(\therefore\) Rate of reaction \(=-\frac{(0.10-0.20)}{13.06}\)
\(R=\frac{0.10}{13.06}\)
\(R=7.2\times10^{-3}\,MS^{-1}\)
\(R=K[A][B]^2\)
\(7.2\times10^{-3}=K\times0.20\times(120)^2\)
\(K=\frac{7.2\times10^{-3}}{0.20\times120}\)
\(K=2.5\times10^{-6}\,M^{-2}S^{-1}\)