Question

 For a reaction , A + B → C+D  the initial rate for different reactions and initial concentrations of reactants are given below:

S.NO.	Initial Conc.		Initial rate (mole L–1 sec–1)
	[ A] mole L–1	[B] mole L–1
1	1.0	1.0	`2xx10^-3`
2	2.0	1.0	`4xx10^-3`
3	4.0	1.0	`8xx10^-3`
4	1.0	2.0	`2xx10^-3`
5	1.0	4.0	`2xx10^-3`

(i) What is the overall order of reaction?
(ii) Write the rate law equation.

Answer 1

`r = K[A]^x[B]^y`
`2xx10^-3=k(1)^x(1)^y`............(1)
`4xx110^-3 = k(2)^x (1)^y`............(2)
`8xx10^-3 = k (4)^x (1)`..........(3)
`2xx10^-3= k(1)^x (2)^y`...........(4)
`2xx10^-3 = k(1)^x (4)^y`............(5)

from eq. (1) & (2)
`(2xx10^-3)/(4xx10^-3) = (k(1)^x(1)^y)/(k(1)^x(2)^y)`
`1/1=((1)/(2))^y`
∴ y = 0
(i) Order of reaction = x + y
                                 = 1 + 0 = 1 

(ii) Rate law r = k [A]¹ [B]⁰