Question

Consider the reaction, $2N{O}_2(g)\to 2NO(g)+O_2(g)$. In the figure below, identify the curves $X,Y$ and $Z$ associated with the three species in the reaction,

• A. $X=NO,Y=O_2,Z=N{O}_2$
• B. $X=O_2,Y-NO,Z=N{O}_2$
• C. $X=N{O}_2,Y=NO,Z=O_2$
• D. $X=O_2,Y=N{O}_2,Z=NO$

Answer 1

Answer: (A)

$2N{O}_2\left(g\right)\to 2NO\left(g\right)+O_2\left(g\right)$
$r=-\frac{1}{2}\frac{d\left[N{O}_2\right]}{dt}$
$=+\frac{1}{2}\frac{d\left[NO\right]}{dt}=+\frac{d\left[O\right]}{dt}$
From the above rate equation, it is clear that rate of disappearance of $N{O}_2$ is equal to the rate of formation of $NO$.
Thus, the curve $X$ is associated with $NO$, $Y$ with $O_2$ and $Z$ with $N{O}_2$.