## Chemistry 9th Edition

$H_2O$: 4 molecules $CO$: 2 molecules $H_2$: 4 molecules $CO_2$: 4 molecules
We are given the equation $H_2O+CO\rightleftharpoons H_2+CO_2$ with $K=2.0$. We are also given that there are 14 O, 6 C, and 16 H atoms. We must determine the number of molecules of $H_2O$, $CO$, $H_2$, $CO_2$ which satisfy the equation $2.0=\frac{[H_2][CO_2]}{[H_2O][CO]}$. Through trial-and-error, we get $2.0=\frac{4\times 4}{4\times 2}$.