Le Chatelier's Principle

[Jessica Castellanos]

Just to make sure, changing the pressure does affect the way the equilibrium will shift only if the change in pressure is from the change in volume?

[JasonLiu_2J]

That is correct. Changing pressure only causes an equilibrium shift when the change in pressure comes from a change in volume, since this also leads to a change in concentration for the reactants and products. Changing pressure through the addition of an inert gas which doesn't affect concentrations of reactants or products will not cause a shift in equilibrium.

[GFolk_1D]

Also, if the moles of gas on either side of the reaction (and therefore space taken up in the volume) are equal than a change in pressure has no effect