Question

The following reaction is exothermic:

             2SO2(g)    +     O2(g)     <=>      2SO3(g)

a.   What is the effect of increasing the temperature of the reaction mixture?

b.  What effect would an increase in pressure have on the reaction mixture?

c.  what effect would it have when SO3 is removed from the reaction mixture?

Answer 1

Let us write the reaction mentioned

2SO_2(g) + O_2(g)      ----------> 2SO_3(g)

The reaction is exothermic

We will apply Le Chatelier's principle to answer all the question

a) effect on increasing the temperature of the reaction mixture

As per Le chatelier's principle whenever a change is made in the system. The equilibrium shifts in such a way so as to negate the change that has been made. Now the reaction is exothermic, which means as the reactants react to produce product the temperature of the system increases. Now if we increase the temperature the equilibrium will try to negate this change. Hence the equilibrium will move in a direction where temperature is less. As discussed above Product temperature is high due to exothermic reaction. Hence the equilibrium will move towards left side to reduce the temperature

Hence on increasing the temperature of the reaction mixture, The equilibrium will shift towards left and less product will be formed

b) effect on increase in pressure of the reaction mixture

On increasing the pressure, the equilibrium will try to negate this.it will try to move in a direction where pressure is less. Where there are lesser molecules, there will be lesser collisions, hence lesser pressure, Hence the equilibrium will move in a direction where there are lesser number of moles. In the reaction, on reactant side we have total number of moles as 3 and on product side we have total number of moles as 2, hence the equilibrium will tend to shift towards right

Hence, on increasing the pressure of the reaction mixture, the equilibrium will shift towards left and more product will be formed

c) effect of removing SO3 from the reaction mixture

Now SO3 is the product here. Now if the product is removed, as per Le chatelier's principle the equilibrium will move in such the direction so as to negate this change. As the product is removed, more amount of reactant will react to produce product.

Hence on removing SO3 from the reaction mixture, The equilibrium will shift to right and more amount of product will be formed