# Does the way a reaction with gas moles shifts depend on Q or number of moles on either side of the reaction?

Given a container with the reaction $\ce{C2H4{(g)} + HCl{(g)} -> C2H5Cl{(g)}}$, if we inject $\ce{C2H5Cl{(g)}}$ to the container, what will happen?

I thought of this in two different ways and got two different answers:

1. If we inject $\ce{C2H5Cl{(g)}}$, $Q>K$ so reaction will shift to the left, leading to the formation of more $\ce{C2H4{(g)} and HCl{(g)}}$.
2. Injecting $\ce{C2H5Cl{(g)}}$ also increases the pressure I suppose, and if you increase pressure, the reaction will shift to the side with the least moles of gas. In this case, it will shift right, forming more $\ce{C2H5Cl{(g)}}$