Given the reaction between two gases represented by $A_2$ and $B_2$ to give the compound $A B(g)$.…
Given the reaction between two gases represented by $A_2$ and $B_2$ to give the compound $A B(g)$.
$A_2(g)+B_2(g) \rightleftharpoons 2 A B(g)$
At equilibrium, the concentration of $A_2=3.0 \times 10^{-3} \mathrm{M}$
of $B_2=4.2 \times 10^{-3} \mathrm{M}$
of $A B=2.8 \times 10^{-3} \mathrm{M}$
If the reaction takes place in a sealed vessel at $527^{\circ} \mathrm{C}$, then the value of $K_c$ will be
2.0
1.9
0.62
4.5
Solution
$A_2(g)+B_2(g) \rightleftharpoons 2 A B(g)$
The equilibrium constant is given by
$\begin{aligned}
K_c=\frac{[A B]^2}{\left[A_2\right]\left[B_2\right]} & =\frac{\left(2.8 \times 10^{-3}\right)^2}{\left(3.0 \times 10^{-3}\right)\left(4.2 \times 10^{-3}\right)} \\
& =\frac{7.84}{12.6} \\
& =0.62
\end{aligned}$