Question

The following reaction is at equilibrium:

2 Fe(OH)₃(s) ↔ Fe₂O₃(s) + 3 H₂O(g); H^o > 0.

Which of the following changes will result in a decrease in the concentration of water (gas)?

	1.	Increasing the temperature.
	2.	Decreasing pressure.
	3.	Adding a catalyst.
	4.	Adding some Fe(OH)3.
	5.	Decreasing the volume.
	6.	Removing some Fe2O3.

Answer 1

1)

Increasing Temperature will shift the reaction in a direction which absorbs heat as per Le chatelier Principle

Forward reaction is endothermic in nature

hence, forward reaction will be favoured

So, Equilibrium moves to product side

So, concentration of H2O would increase

2)

Decrease the pressure will shift the reaction in a direction which have greater gaseous molecules as per Le chatelier Principle

Here product has more gaseous molecule

So equilibrium will move to right

So, Equilibrium moves to product side

So, concentration of H2O would increase

3)

Catalyst doesn't affect equilibrium

So, No effect on equilibrium

So, concentration of H2O would not change

4)

Adding solid or liquid doesn't affect equilibrium

So, No effect on equilibrium

So, concentration of H2O would not change

5)

Decreasing volume will increase the pressure which in turn shift the reaction in a direction which have lesser gaseous molecules as per Le chatelier Principle

Here reactant has less gaseous molecule

So equilibrium will move to left

So, Equilibrium moves to reactant side

So, concentration of H2O would decrease

6)

Removing solid or liquid doesn't affect equilibrium

So, No effect on equilibrium

So, concentration of H2O would not change

Answer: option 5