# Question #49fdc

Nov 16, 2015

See explanation.

#### Explanation:

I am not sure why the answer is missing a very essential point which is teaching the student Le Châtelier's principle . Maybe this is not a grade 12 question!!!!

The student could easily deduce that since the $\left[{I}_{2}\right] = 0 M$ the equilibrium will shift toward the direction of making ${I}_{2}$ and therefore to the left and in this case, the ICE table is written as follows:

$\text{ " " " " " " " " } {H}_{2} \left(g\right) + {I}_{2} \left(g\right) r i g h t \le f t h a r p \infty n s 2 H I \left(g\right)$
$I n i t i a l \text{ " " " " "8M" " "0M" " " " } 2.4 M$
$\text{Change" " " " " " "+x" +x" " " " } - 2 x$
$E q u i l i b r i u m \text{ "8+x" " x" " " } 2.4 - 2 x$

In this case, ONLY $\textcolor{g r e e n}{\text{positive}}$ values of $x$ will be accepted.

However, the way the answer is written is that he will assume that the equilibrium is shifting to the right and in this case $x$ will be $\textcolor{g r e e n}{\text{positive}}$, however, if his assumption is wrong, $x$ will be $\textcolor{red}{\text{negative}}$ and this is the case, that is why the $\left[H I\right]$ dropped from $2.4 M$ to $2.2 M$.