Question

. Consider the endothermic reaction: Fe³⁺(aq) + Cl^-(aq)   → FeCl²⁺(aq).

Use Le Châtelier’s principle to predict how the equilibrium concentration of the complex ion FeCl²⁺ will change when:

  

(3.1) Fe(NO₃)₃ is added   

(3.2) Cl^- is precipitated as AgCl by addition of AgNO₃  

(3.3) The temperature is increased   

(3.4) A catalyst is added

(3.5) The pressure of the system is increased

Answer 1

Answers:

3.1. When Fe(NO₃)₃ is added, the concentration of Fe³⁺ which is a reactant increases and it increases the equilibrium concentration of FeCl²⁺ by favouring the forward reaction.

3.2. When Cl^- is precipitated, the reactant concentration decreases and the reaction is favoured more in backward direction than forward direction and this results in decrease of the equilibrium concentration of FeCl²⁺.

3.3. As the temperature is increased, the equilibrium concentration of FeCl²⁺ increases as the reaction is endothermic in forward direction.

3.4. As catalyst increases the rate of both forward and backward reaction, the equilibrium concentration of FeCl²⁺ will remain unchanged. However, the equilibrium is achieved at a faster rate.

3.5. As the reaction is purely dealing with aqueous phase and no gaseous phase, so increasing the pressure won't affect the reaction rate or the equilibrium concentration of FeCl²⁺.