Question

The data for the reaction $A+B\to C$ is:

Exp.	$[A{]}_0$	$[B{]}_0$	initial rate
1.	0.012	0.035	0.10
2.	0.024	0.035	0.080
3.	0.012	0.070	0.10
4.	0.024	0.070	0.80

The rate law corresponding on above data is :

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

Answer 1

Answer: (B)

$r=k[A{]}^3$

In Exp 1 and 3 (Keeping the Conc of [A] same), when the conc of [B] is doubled, there was no change in the rate.So, the Order wrt [B] is '0'.

In Exp 3 and 4 (Keeping the Conc of [B] same), when the conc of [A] is doubled, the rate was increased 8 times. So, the Order wrt [A] is '3'

$r=k[A{]}^3$