Question

A hypothetical reaction `A_(2) + B_(2) rarr 2AB` follows the mechanism as given below:
`A_(2) hArr A+A ("fast")`
`A+B_(2) rarr AB+B` (slow)
`A+B rarr AB` (fast)
The order of the overall reaction is
A. `2`
B. `1`
C. `3//2`
D. Zero

Answer 1

Correct Answer - c
`r=K[A][B_(2)]`
and `K_(c )=([A][A])/([A_(2)])` or `[A]=K_(c )^(1//2)[A_(2)]^(1//2)`
Thus `r=K.K_(c )^(1//2)[A_(2)]^(1//2)[B_(2)]`
`=K^(1)[A_(2)]^(1//2)[B_(2)]` or order is `3//2`.