Question

For a reaction, $A+B⟶C+D$, if the concentration of $A$ is doubled without altering the concentration of $B$, the rate gets doubled. If the concentration of $B$ is increased by nine times without altering the concentration of $A$, the rate gets tripled. The order of the reaction is:

• A. $2$
• B. $1$
• C. $3/2$
• D. $4/3$

Answer 1

The correct option is C $3/2$

Rate $=k{\left[A\right]}^{\alpha }{\left[B\right]}^{\beta }$

...(i)
$2\times$ rate $=k{\left[2A\right]}^{\alpha }{\left[B\right]}^{\beta }$ ....(ii)

$3\times$ rate $=k{\left[A\right]}^{\alpha }{\left[9B\right]}^{\beta }$ ...(iii)

From equations (i) and (ii), $\alpha =1$

From equations (i) and (iii), $\beta =1/2$

Order $=\alpha +\beta =1+\frac{1}{2}=\frac{3}{2}$