The air oxidation of nitric oxide is one of the reactions that contributes to the formation of acid rain:
`2NO(g)+O_(2)(g)rarr 2NO_(2)(g)`
Some initial rate data are collected

Two overall order of the reaction is

Options

A. two
B. three
C. one
D. zero

Answer

B

Explanation

Note that pairs of experiments are designed to invertigate the effect on the intial rate of a change in the intial concentration of a single reactant.
In the first two experments, the concentration of `NO` is doubled from `0.015M` to `0.03M` while the concentration of `O_(2)` is held constant. The intial rate increases by a factor of `4` , from `0.048Ms^(-1)` to `0.192Ms^(-1)` , indicating that the rate depends on the concentration of `NO` squared, `[NO]^(-2)` . When `[NO]` is held constant and `[O_(2)]` is doubled (experiments `1` and `3`), the intial rate doubles from `0.048Ms^(-1)` to `0.096Ms^(-1)` , indicating that the rate depends on the rate concentration of `O_(2)` to the first power, `[O_(2)]^(1)` . Therefore, the rate law for formation of `NO_(2)` is
Rate `=(d[NO_(2)])/(dt)=K[NO]^(2)[O_(2)]`
The overall reaction order s three. In accord with this rate law, which is second order in `NO` , first order in `O_(2)` , and third order overall, the intial rate increases by a factor of `8` when the concentratiobn of both `NO` and `O_(2)` are doubled (experiments `1` and `4`).