1. The problem statement, all variables and given/known data In what direction will the reaction go if the volume is increased. PCl5⇔ PCl3 + Cl2 3. The attempt at a solution I would think using the ideal gas equation PV = nRT that since V goes up P must go down. In order for P to go down you need less molecules. There are less molecules on the left side of the equation, so the direction should be to the left but the book says to the right.