Question

The following reaction has achieved equilibrium. Predict the effect on the formation of phosphorous pentachloride (increase, decrease or no effect) for the stated changes to the system:

PCl5(g)←→PCl3(g)_Cl2(g)

A) The concentration of phosphorous trichloride is increased.

B) The concentration of chlorine is increased.

C) The volume of the container in which the reaction is taking place is suddenly made smaller.

D) The pressure of the system is increased by adding one atmosphere of gaseous nitrogen to the container.

Could you please explain your answers? Thank you!

Answer 1

1)
we are adding a product
According to Le Chatelier's Principle,
Adding product will shift reaction towards reactant side
Equilibrium moves to reactant side
So, PCL5 will increase
2)
we are adding a product
According to Le Chatelier's Principle,
Adding product will shift reaction towards reactant side
Equilibrium moves to reactant side
So, PCL5 will increase

3)
We are decreasing volume here
In other words we are trying to increase pressure
so, according to Le Chatelier's principle,
Reaction will try to decrease the pressure
Hence it will move in a direction which have lesser gaseous molecules
Here reactant has less gaseous molecule
So equilibrium will move to left
Equilibrium moves to reactant side
So, PCL5 will increase
4)
We are increasing pressure here
so, according to Le Chatelier's principle,
Reaction will try to decrease the pressure
Hence it will move in a direction which have lesser gaseous molecules
Here reactant has less gaseous molecule
So equilibrium will move to left
Equilibrium moves to reactant side
So, PCL5 will increase