Question

The equilibrium constant at 850 K for the reaction
$N_2\left(g\right)+O_2\left(g\right)\leftrightharpoons 2NO\left(g\right)$ is 0.5625. The equilibrium concentration of $NO\left(g\right)$ is $3.0\times {10}^{-}3M$
If the concentration of $N_2\left(g\right)$ and $O_2\left(g\right)$ are equal, the concentration of $N_2\left(g\right)$ in M is:

• A. $4.0\times {10}^{-3}$
• B. $4.0\times {10}^{-2}$
• C. $1.6\times {10}^{-3}$
• D. $3.0\times {10}^{-3}$

Answer 1

The correct option is A $4.0\times {10}^{-3}$

$K_{eq}=\frac{[NO{]}^2}{\left[N_2\right]\left[O_2\right]}$
$0.5625=\frac{[3.0\times {10}^{-3}{]}^2}{\left[x\right]\left[x\right]}$ , $x=\left[N_2\right]=\left[O_2\right]$
$\left[N_2\right]=4.0\times {10}^{-3}M$