Question

Le Chatelier's Principle is applicable to: (a) Heterogenous reaction (b) Homogenous reaction (c) Irreversible reaction (d) System in equilibrium

Short answer

Le Chatelier's Principle applies to systems in equilibrium.

Step-by-step solution

Understand Le Chatelier's Principle

Le Chatelier's Principle states that if a system at equilibrium is subjected to a change in concentration, pressure, volume, or temperature, the system will adjust itself to partially counteract that change and reach a new equilibrium.

Analyze Options Given

Consider each option: (a) Heterogeneous reaction refers to reactions involving substances in different phases. (b) Homogeneous reaction involves substances in the same phase. (c) Irreversible reaction is one that goes to completion and does not come to equilibrium. (d) System in equilibrium means the forward and reverse reactions occur at the same rate.

Apply Le Chatelier's Principle

Le Chatelier's Principle only applies to systems that can achieve or are at equilibrium. Comprehend that the principle is about how a system in equilibrium responds to disturbances to restore a state of balance.

Identify Consistent Option

The principle is applicable to systems in equilibrium, hence option (d) is appropriate. Irreversible reactions (option c) are not applicable since they don't achieve equilibrium.

Key concepts

Equilibrium Reactions

In chemistry, equilibrium reactions are those where the reactants and products of a reaction can convert back and forth. This means the forward reaction (reactants turning into products) and the reverse reaction (products turning back into reactants) occur simultaneously. A state of balance is reached when the rate of the forward reaction equals the rate of the reverse reaction. At this point, the concentrations of reactants and products remain constant, though not necessarily equal.

Equilibrium can only be achieved in reactions where both forward and reverse pathways are possible. It's an essential concept to understand because it reflects the dynamic nature of chemical systems. This balance is not static but flexible, and can be shifted by changes in the reaction conditions. These include changes in pressure, concentration, or temperature, which is where Le Chatelier's Principle becomes important. The principle describes how such changes will affect the system and how it will adjust to return to equilibrium.

Homogeneous and Heterogeneous Reactions

Reactions in chemical systems are classified as either homogeneous or heterogeneous based on the phases of the reactants and products involved.

• **Homogeneous Reactions**: These reactions occur when the reactants and products are in the same phase. A common example is a reaction in a gas mixture or in a single liquid solution, where all the substances involved are in the gas or liquid phase.


• **Heterogeneous Reactions**: Here, the reactants and products occur in different phases. A classic example is a reaction between a solid catalyst and gaseous reactants. The interaction at the boundary surfaces plays a significant role in the progress of the reaction.

Understanding the difference between these two types of reactions is crucial because it affects the methods used to analyze the reactions. For example, measuring concentrations is straightforward in homogeneous reactions, whereas surface area and interface interactions are more critical in heterogeneous reactions. Both types can reach equilibrium under the right conditions, and Le Chatelier's Principle applies to both, assuming they can achieve equilibrium.

Chemical Equilibria

Chemical equilibria signify the condition of a chemical reaction when both the forward and reverse reactions proceed at the same rate. This equilibrium is dynamic, meaning that although individual molecules are continuously reacting, their concentrations remain constant over time. It is key to realize that reaching equilibrium doesn't mean the reactants and products are present in equal amounts, but that no net change is observed.

• **Static vs Dynamic Equilibrium**: While static suggests no movement, dynamic indicates continuous action, though balanced.


• **Factors Affecting Equilibrium**: Concentration, pressure, and temperature changes can shift equilibrium positions, making the study of how equilibrium responds crucial for chemical processes.

For systems at equilibrium, Le Chatelier's Principle offers insights into how external disturbances, such as changing temperatures or adding more reactants, affect the system's balance. Understanding chemical equilibria is crucial in predicting how changes will influence a chemical system, allowing chemists to control reaction conditions and optimize yields.