Explain Le Chatelier s Principle and how it app... - SS3 Chemistry Chemical Equilibrium Question

Le Chatelier's Principle states that when a system at equilibrium is subjected to a change in conditions, it will respond in a way that counteracts the change and re-establishes a new equilibrium. This principle applies to chemical equilibrium, where reversible reactions reach a point where the rates of the forward and reverse reactions are equal, and the concentrations of reactants and products remain constant over time.

1.    Effect of Changes in Concentration:

●     If the concentration of a reactant is increased, the system will shift to consume some of the additional reactants by favouring the forward reaction until a new equilibrium is reached. This shift increases the concentration of products.

●     If the concentration of a product is increased, the system will shift to consume some of the additional product by favouring the reverse reaction until a new equilibrium is established. This shift increases the concentration of reactants.

Example: Consider the reaction N2(g) + 3H2(g) ⇌ 2NH3(g). If more N2 is added, the system will shift to the right to produce more NH3 and consume the extra N2.

2.    Effect of Changes in Pressure (for Gaseous Reactions):

●     An increase in pressure will shift the equilibrium position towards the side with fewer moles of gas to reduce the pressure.

●     A decrease in pressure will shift the equilibrium towards the side with more moles of gas to increase the pressure.

Example: For the reaction N2(g) + 3H2(g) ⇌ 2NH3(g), increasing the pressure will shift the equilibrium to the right (towards NH3) since there are fewer moles of gas on the product side.

3.    Effect of Changes in Temperature:

●     If a reaction is exothermic (releases heat), an increase in temperature will shift the equilibrium position to the left, favouring the endothermic direction to absorb the extra heat.

●     If a reaction is endothermic (absorbs heat), an increase in temperature will shift the equilibrium to the right, favouring the exothermic direction to produce more heat.

Example: For the reaction N2(g) + O2(g) ⇌ 2NO(g) + heat, increasing the temperature will shift the equilibrium to the right, favouring the endothermic direction to absorb the additional heat.

Le Chatelier's Principle is a fundamental concept in understanding the behaviour of chemical equilibria and provides insights into how systems respond to external changes. It has practical applications in industries where reversible reactions are essential, such as the Haber-Bosch process for ammonia production, where optimising reaction conditions based on Le Chatelier's Principle increases efficiency and yield.