Question

For reaction: A + B $\to$ Products, the rate if the reaction at various concentration are given below:

$\begin{array}{cccc}\text{Expt. No.}& \text{(A)}& \text{(B)}& \text{Rate}\\ 1& 0.2& 0.2& 2\\ 2& 0.2& 0.4& 4\\ 3& 0.6& 0.4& 36\end{array}$

• A. $\text{Rate}=k\left[A{]}^2\right[B{]}^2$
• B. $\text{Rate}=k\left[A{]}^2\right[B]$
• C. $\text{Rate}=k\left[A\right][B{]}^2$
• D. $\text{Rate}=k\left[A{]}^3\right[B]$

Answer 1

The correct option is B

$\text{Rate}=k\left[A{]}^2\right[B]$

Let the rate law be $r=k\left[A{]}^x\right[B{]}^y$
Divide (2) by (1)
$\therefore 2=\left[2\right]y,y=1$
Divide (3) by (2)
$\therefore 9=(3{)}^x,x=2$
Hence rate equation, $R=k\left[A{]}^2\right[B{]}^1$