Answer:
[tex]-r_{O_2}=1\times{10}^{-5}\frac{M}{s}[/tex]
Explanation:
The decomposition of [tex]NO_2[/tex] follows the equation
[tex]2NO_2\rightarrow2NO+O_2[/tex]
By definition, the rate of a chemical reaction can be expressed by
[tex]-r_{NO_2}=\frac{d\left[NO_2\right]}{dt}=\frac{0.010-0.008\ M}{100\ s}=2\times{10}^{-5}\frac{M}{s}[/tex]
The rate of appearance of [tex]O_2[/tex] is related to the rate of disappearance of [tex]NO_2[/tex] by the stoichiometry. This means that, for each mole of [tex]O_2[/tex] that appears 2 moles of [tex]NO_2[/tex] are consumed. So
[tex]-r_{O_2}=-r_{NO_2}\times\frac{1\ mole\ \ O_2}{2\ mole\ \ {\rm NO}_2}=1\times{10}^{-5}\frac{M}{s}[/tex]