you are given a closed container in which PCl5(g), PCl3(g) and Cl2(g) are in equilibrium with each other at 546K .
explain what influence the addition of Cl2 to the container will have on the equilibrium ( explain in terms of [PCl5] ) :
can someone explain this to me :)

Question

you are given a closed container in which PCl5(g), PCl3(g) and Cl2(g) are in equilibrium with each other at 546K . 
explain what influence the addition of Cl2 to the container will have on the equilibrium ( explain in terms of [PCl5] ) :
can someone explain this to me :)

jfraser · Answer

a system that is at equilibrium is very much like a see-saw: everything is "balanced". a shift in the balance will cause a stress on the system. The system will then move to relieve the stress by moving some mass from one side to another. It will shift the reaction forward or backwards in order to reestablish its equilibrium and its balance. In the equation you have:$$PCl_{3}(g) + Cl_{2}(g) \leftarrow \rightarrow PCl_{5}(g)$$ adding Cl2 gas will create an imbalance of reactants. The system has to shift to "relieve the stress" and use up some of that excess Cl2 and make more products. The concentration of PCl5 has to increase as a result of this sress.