# The reaction rate law is known to be 2nd order, and for an initial concentration [NO2(g)]o=0.0100M, the initial rate is 0.0350 M/s. Write the rate law, and give the value of the rate constant?

## Consider the following reaction: 2 NO2(g) -> 2 NO(g) + O2(g) The reaction rate law is known to be 2nd order, and for an initial concentration [NO2(g)]o=0.0100M, the initial rate is 0.0350 M/s. Write the rate law, and give the value of the rate constant.

Dec 12, 2016

The rate law is "rate" = k["NO"_2]^2; $k = \text{350 L·mol"^"-1""s"^"-1}$.

#### Explanation:

${\text{2NO"_2 → "2NO" + "O}}_{2}$

If the reaction is second order and ${\text{NO}}_{2}$ is the only reactant, the rate law is

"rate" = k["NO"_2]^2

$k = \text{rate"/(["NO"_2]^2) = ("0.0350 mol·L"^"-1""s"^"-1")/("0.0100 mol·L"^"-1")^2 = "350 L·mol"^"-1""s"^"-1}$