pcl3(g) cl2(g) �¨ <--- pcl5(g) Energy Some PCl3 and Cl2 are mixed in a container at 200 degrees celius and the system reaches equilibrium according to the equation above. Which of the following causes and increase in the number of moles of PCl5 present at equilibrium? I. Drcreasing the volume of the container II. Raising th etemperature III. Adding a mole of He gas at constant volume

Question

Help!!!

Answer 1

Note that you have the equation going from right to left. If that's the way you want it, ok.

This is Le Chatelier's Principle which, in basic words, tells us that when we stress a system at equilibrium it will try to undo what we did to it. I'm going to rewrite the equation this way,
PCl3(g) + Cl2(g) <==> PCl5(g) + energy but actually it makes no difference since the problem tells us it has reached equilibrium.
Here is what you need to know about Le Chatelier's Principle.
1. An increase in P makes the GASEOUS system move to the side with fewer mols of gas.
2. An increase in reactant or product makes the system move to the other side.
3. Treat T changes as if it were the same as #2.
3. Adding an intert gas has no effect on th equilibrium.
I'll go through I and you do the rest.
A decrease in volume means an increase in pressure, that means the reaction shifts to the side with fewer mols and in this case that's the side with PCl5 so it will increase. The PCl5 side has 1 mol gas and the other side has 2 mols gas.