7.1Chemical Equilibria: Reversible Reactions & Dynamic Equilibrium

Flashcards covering key concepts in chemical equilibria, including reversible reactions, Le Chatelier's Principle, effects of changes in system conditions, and equilibrium constants.

What is a reversible reaction?

A reversible reaction is one where products can react to reform the original reactants.

What symbols are used to represent a reversible reaction?

Two opposing half arrows (⇌) are used to show a reversible reaction.

What is dynamic equilibrium?

Dynamic equilibrium occurs when the rate of the forward reaction equals the rate of the backward reaction, and the concentrations of reactants and products remain constant.

In a closed system at dynamic equilibrium, what remains unchanged?

The concentrations of reactants and products remain constant.

What is Le Chatelier's Principle?

Le Chatelier's Principle states that if a change is made to a system at dynamic equilibrium, the position of equilibrium will shift to minimize that change.

How does increasing the concentration of reactants affect equilibrium?

Increasing reactant concentration shifts equilibrium to the right, favoring product formation.

How does changing pressure affect equilibrium in gas reactions?

Increasing pressure shifts equilibrium toward the side with fewer gas molecules.

What is the effect of temperature on an endothermic reaction at equilibrium?

Increasing temperature shifts the equilibrium to the right, favoring the products.

How do catalysts affect equilibrium?

Catalysts speed up the rate of reaching equilibrium but do not affect the position of the equilibrium.

What does the equilibrium constant K represent?

The equilibrium constant K expresses the ratio of the concentrations of products to reactants at equilibrium.

What is the equilibrium expression for the reaction aA + bB ⇌ cC + dD?

Kc = [C]^c [D]^d / [A]^a [B]^b.

What happens to the equilibrium constant when temperature changes?

The equilibrium constant K changes with temperature, depending on whether the reaction is endothermic or exothermic.

How is the partial pressure of a gas defined?

The partial pressure of a gas is the pressure that the gas would exert if it occupied the entire container alone.

What does the mole fraction of a gas indicate?

The mole fraction is the ratio of the moles of a particular gas to the total number of moles of gas present.

How are equilibrium expressions written in terms of partial pressures?

Equilibrium expressions involving partial pressures are written similarly to those involving concentrations, but use pressures (p) instead.

How does the presence of a catalyst in a reaction system affect the value of K?

A catalyst does not change the value of the equilibrium constant K; it only speeds up the rate at which equilibrium is reached.

In the Haber process, what effect does increasing pressure have on ammonia yield?

Increasing pressure shifts the equilibrium to the right, increasing ammonia yield.

What compromise is often made regarding temperature in the Haber process?

A compromise temperature of 400–450°C is used to optimize the reaction rate and ammonia yield.

What role does vanadium(V) oxide play in the Contact process?

Vanadium(V) oxide acts as a catalyst to increase the rate of reaction for sulfuric acid production.

What is the industrial pressure commonly used in the Contact process?

An industrial pressure of approximately 1 atm is used to save costs while achieving sufficient yield.