Question

The expression for equilibrium constant, $K_c$ for the following reaction is
$2Cu(NO_3)_{2(s)} \rightleftharpoons 2CuO_{(s)} +4NO_{2(g)} +O_{2(g)}$

• A. $K_{c}=\frac{\left[CuO_{\left(s\right)}\right]^{2}\left[NO_{2\left(g\right)}\right]^{4}\left[O_{2\left(g\right)}\right]}{\left[Cu\left(NO_{3}\right)_{2\left(s\right)}\right]^{2}}$
• B. $K_{c}=\frac{\left[NO_{2\left(g\right)}\right]^{4}\left[O_{2\left(g\right)}\right]}{\left[Cu\left(NO_{3}\right)_{2\left(s\right)}\right]^{2}}$
• C. $K_{c}=\left[NO_{2\left(g\right)}\right]^{4}\left[O_{2\left(g\right)}\right]$
• D. $K_{c}=\frac{\left[CuO_{\left(s\right)}\right]^{2}}{\left[Cu\left(NO_{3}\right)_{2\left(s\right)}\right]^{2}}$

Answer 1

Answer: (C)

$2Cu(NO_3)_{2(s)} \rightleftharpoons 2CuO_{(s)} +4NO_{2(g)} +O_{2(g)}$
Since conc, of solids is taken as $1$, the expression for $K_c$ becomes
$K_{c}=\left[NO_{2\left(g\right)}\right]^{4}\left[O_{2\left(g\right)}\right]$