Question

An important reaction in the commercial production of hydrogen is

CO(g) + H₂O(g)$\mathbf{\rightleftharpoons }$H₂(g) + CO₂(g)

How will this system at equilibrium shift in each of the five following cases?

a. Gaseous carbon dioxide is removed.

b. Water vapor is added.

c. In a rigid reaction container, the pressure is increased by adding helium gas.

d. The temperature is increased (the reaction is exothermic).

e. The pressure is increased by decreasing the volume of the reaction container.

Short answer

a. This system will shift right.

b. This system will shift right.

c. Adding helium gas has no effect.

d. This system will shift left.

e. It has no effect.

Step-by-step solution

Part a.

The removal of carbon dioxide gas will shift the reaction to the right. Because carbon dioxide is one of the products in this system that need to be produced again to reestablish the equilibrium.

Part b.

At equilibrium, the addition of water vapor will move the reaction to the right to consume some of the water vapor added. Hence, the reaction will move right.

Part c.

Adding helium gas to this system at equilibrium has no effect because helium gas in this reaction is neither a product nor a reactant. Hence, this system has no effect on the equilibrium.

Part d.

The equilibrium reaction will shift left when increasing the temperature because the given reaction is exothermic. So, the temperature of the system gets reduced by consuming some of the heat added.

Part e.

In the given equilibrium reaction, decreasing the volume has no effect on the equilibrium because the moles difference between gaseous products and gaseous reactants is zero. Hence, the volume change has no effect.