Question

What is the effect of increasing the pressure of a reaction mixture at equilibrium if the reactant side has fewer moles of gas particles than the product side?

Short answer

Increasing the pressure of a reaction mixture at equilibrium will shift the equilibrium towards the side with fewer moles of gas, which is the reactant side in this case.

Step-by-step solution

Understand Le Chatelier's Principle

Le Chatelier's Principle states that if a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium will move to counteract the change. This principle can be applied to understand the effects of changes in pressure on a system at chemical equilibrium.

Analyze the Mole Ratio of Gas Particles

Determine the mole ratio of gas particles on both the reactant and product sides of the equilibrium equation. If the reactant side has fewer moles of gas than the product side, an increase in pressure will favour the formation of reactants to reduce the pressure.

Predict the Shift in Equilibrium

When pressure is increased, the system will try to decrease the pressure. In this case, the equilibrium will shift towards the side with fewer moles of gas, which is the reactant side. Hence, an increase in pressure will result in the formation of more reactants.

Key concepts

Chemical Equilibrium

Understanding chemical equilibrium is crucial when studying chemical reactions. It is a state in which the rate of the forward reaction equals the rate of the reverse reaction, meaning that the concentrations of the reactants and products remain constant over time, not necessarily equal. Think of it as a tug-of-war where both teams are exerting equal force; nobody moves, but the tension is dynamic.

At equilibrium, reactions continue to occur, but there are no net changes in the concentrations of the reactants and products. This concept is foundational in understanding how various factors, such as pressure, temperature, and concentration changes, can shift the equilibrium position to favor either the production of reactants or products. Le Chatelier's Principle provides a qualitative prediction on how these changes can affect the equilibrium state.

Pressure Effects on Equilibrium

Le Chatelier's Principle also sheds light on how pressure changes can impact a system at equilibrium, specifically for reactions involving gases. An increase in pressure, achieved by reducing the volume of the container for a gaseous reaction, or adding a gas to a mixture at constant volume, causes the system to adjust in a way that counteracts this change.

If you add pressure to the system, the equilibrium will shift toward the side with fewer moles of gas because this will result in a lower overall volume, thus relieving some of the added pressure. Conversely, if pressure is decreased, the system will shift toward the side with more moles of gas. Understanding these pressure effects allows chemists to manipulate the conditions to favor the formation of desired products.

Mole Ratio of Gas Particles

The mole ratio of gas particles involved in a reaction is another pivotal concept. It refers to the number of moles of gaseous reactants compared to gaseous products. If a reaction has more moles of gas on the product side than the reactant side and the pressure is increased, Le Chatelier's Principle predicts that the system will shift toward the side with fewer moles of gas — the reactants in this scenario.

Chemists use the mole ratio to predict how changes in conditions, like pressure, will drive the equilibrium position of a gaseous reaction. This quantitative aspect allows for precise adjustments in reaction conditions to optimize yield, making it a powerful tool in industrial and laboratory chemical synthesis.