Consider the reaction 4 NH₃(𝑔) + 5 O₂(𝑔) ⇌ 4 NO(𝑔) + 6 H₂O(𝑔), Δ𝐻 = −904.4 kJ Does each of the following increase, decrease, or leave unchanged the yield of NO at equilibrium? (e) add a catalyst

Key Concepts

Chemical Equilibrium

Chemical equilibrium occurs when the rates of the forward and reverse reactions are equal, resulting in constant concentrations of reactants and products. In this state, the system is dynamic, meaning that reactions continue to occur, but there is no net change in the amounts of substances. Understanding this concept is crucial for analyzing how changes in conditions affect the yield of products in a reaction.

Le Chatelier's Principle

Le Chatelier's Principle states that if a system at equilibrium is subjected to a change in concentration, temperature, or pressure, the system will adjust to counteract that change and restore a new equilibrium. This principle helps predict how the yield of products, such as NO in the given reaction, will respond to various alterations in the system, including the addition of reactants or products.

Role of Catalysts

A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. It works by lowering the activation energy required for the reaction to occur. Importantly, while a catalyst speeds up the attainment of equilibrium, it does not change the position of the equilibrium or the yield of products at equilibrium, meaning it does not affect the concentrations of reactants or products once equilibrium is reached.