Question

For the following reaction, the equilibrium constant $K_c$ at $298K$ is $1.6x10^{17}$.
$\mathrm{Fe}{}^{2+}(\mathrm{aq})+\mathrm{S}{}^{2-}(\mathrm{aq})\rightleftharpoons \mathrm{FeS}(\mathrm{s})$
When equal volumes of $0.06$ M $F{e}^{2+}(aq)$ and $0.2$ M $S^{2-}(aq)$ solutions are mixed, the equilibrium concentration of $F{e}^{2+}$ (aq) is found to be $Y\times 10^{17}$ M. The value of $Y$ is______

Answer 1

Answer: 8.93

$F{e}^{2+}\left(aq\right)+S^{2-}\left(aq\right)\rightleftharpoons FeS\left(s\right),K=1.6\times 10^{17}$
$t_{0}0.030.1-$
$t_{aq}\times 0.1-0.03-$
$\simeq 0.07$
$\therefore x\left(0.7\right)=\frac{1}{1.6}\times 10^{-17}$
$\Rightarrow x=8.93\times 10^{-17}M$
$\therefore Y=8.93$