Conisder a reaction `aG+bH rarr` Products. When concentration of both the reactants `G` and `H` is doubled, the rate increases eight times. However, when the concentration of `G` is doubled, keeping the concentration of `H` fixed, the rate is doubled. The overall order of reaction is

Options

A. 0
B. 1
C. 2
D. 3

Answer

D

Explanation

Rate `r=k[G]^(alpha)[H]^(beta) k x^(alpha)y^(beta)`…(i)
When the concentration of both G and H is doubled
`8r =k(2x)^(alpha)(2y)^(beta)=2^(alpha+beta)kx^(alpha)y^(beta)`….(ii)
When concentration of only G is doubled
`2r = k(2x)^(alpha)(y)^)beta) =2^(alpha)k x^(alpha)y^(beta)`....(iii)
(iii)/(i) gives `2 = 2^(alpha):. alpha =1`
(iii)/(ii) gives `4 = 2^(beta) :. beta =2`
Hence overall order of reaction `= 1+2=3`.