IB Chemistry SL Reactivity 2.3

Dynamic Equilibrium

A state in which the rate of the forward reaction equals the rate of the backward reaction in a closed system, with constant concentrations of reactants and products.

Reversible Reactions

Reactions in which products can react to reform the original reactants.

Closure System

A system in which none of the reactants or products escape from the reaction mixture.

Equilibrium Constant (K)

A value that expresses the ratio of product concentrations to reactant concentrations at equilibrium, specific to a given reaction.

Le Chatelier's Principle

States that if a change is made to a system at dynamic equilibrium, the position of the equilibrium will shift to minimize the change.

Equilibrium Law

Explains how the equilibrium constant (K) is derived from the stoichiometry of the reaction.

Effects of Concentration on Equilibrium

Changes in concentration can shift equilibrium to the left or right depending on whether reactants or products are added or removed.

Effects of Temperature on Equilibrium

Changes in temperature will shift equilibrium in the direction that absorbs or releases energy.

Catalysts

Substances that increase the rate of a chemical reaction without affecting the position of equilibrium or the value of K.

Heterogeneous Equilibria

Equilibria involving substances in different phases, where changes in one phase can affect the overall equilibrium.

Forward Reaction

The reaction that proceeds from reactants to products.

Backward Reaction

The reaction that proceeds from products back to reactants.

Equilibrium Expression

Mathematical expression relating the concentrations of reactants and products at equilibrium.

Shift in Equilibrium

A term describing the movement of equilibrium towards reactants or products due to external changes.

Closed System

A system where no materials can enter or leave, allowing equilibrium to be reached.

Open System

A system where reactants or products can escape, preventing equilibrium from being reached.

Equilibration

The process of a reaction reaching a state where the concentrations of reactants and products remain constant.

Equilibrium Mixture

The combination of reactants and products present at equilibrium.

Chemical Equilibrium

The state of a reversible chemical reaction where the rates of the forward and backward reactions are equal.

Static Equilibrium

A state of equilibrium where there are no changes in the system and no movement is occurring.

Dynamic Equilibrium vs. Static Equilibrium

Dynamic equilibrium involves ongoing reactions with constant concentrations, while static equilibrium involves no changes.

Disturbance in Equilibrium

Any change in concentration, temperature, or pressure that affects the position of equilibrium.

Equilibrium Shift Example

In a mixture where reactants are added, the equilibrium will shift toward products to re-establish balance.

Importance of Equilibrium in Chemical Reactions

Understanding equilibrium helps predict the behavior of reactions in various conditions and optimize yields.

K Reaction Quotient

A ratio used to determine the direction in which a reaction will proceed to reach equilibrium.

Applications of Le Chatelier's Principle

Used in industrial processes, such as the Haber process for ammonia production, to maximize product yield.

Factors Affecting Equilibrium

Concentration, temperature, and pressure are key factors that can shift the position of equilibrium.

Equilibrium Systems

Systems where reactants and products coexist stably without net change in composition.

What is the role of equilibrium in reaction dynamics?

Equilibrium helps understand the rates of forward and backward reactions and their impact on the overall reaction progress.

What is a homogeneous equilibrium?

Equilibrium in which all reactants and products are in the same phase.

What does it mean if a reaction is at equilibrium?

It means the concentrations of reactants and products remain constant over time.

What factors influence the position of chemical equilibrium?

Factors include concentration, temperature, and pressure changes.

What happens to equilibrium if pressure is increased in a gaseous reaction?

The equilibrium will shift toward the side with fewer moles of gas to reduce pressure.

What is an example of an industrial application of chemical equilibrium?

The synthesis of ammonia in the Haber process, where conditions are optimized for product yield.

How do catalysts influence chemical equilibrium?

Catalysts speed up the rate of reaching equilibrium but do not change the position of the equilibrium or the equilibrium constant.

What are dynamic changes in equilibrium?

Constant rates of forward and backward reactions that maintain concentrations of reactants and products.

What is the difference between dynamic and static equilibrium?

Dynamic equilibrium involves ongoing reactions with no net change in concentration, while static equilibrium has no reactions occurring.

What does shifting equilibrium mean?

It refers to the movement of equilibrium towards either reactants or products in response to external changes.

What is an example of an effect of concentration change?

If the concentration of products increases, the equilibrium will shift left toward reactants.

What is the significance of the equilibrium constant (K)?

K indicates the extent of a reaction at equilibrium; a large K means products are favored, while a small K indicates reactants are favored.

What role does energy play in temperature changes affecting equilibrium?

Increasing temperature shifts equilibrium in the direction that absorbs energy, while decreasing temperature shifts it to release energy.

What is the response of a system at equilibrium to a change in pressure?

In a gaseous system, increasing pressure shifts the equilibrium to the side with fewer gas moles.

What is the role of heterogeneous equilibria?

Heterogeneous equilibria involve reactants and products in different phases, affecting how changes in one phase influence the system.

What is the importance of chemical equilibrium in industrial processes?

It helps optimize conditions for maximum yield in processes like chemical synthesis, ensuring efficient production.

How do changes in a closed system affect equilibrium?

In a closed system, changes in concentration, temperature, or pressure can shift the equilibrium position to restore balance.

What does a disturbance in equilibrium signify?

Any external change, such as concentration or temperature alteration, that impacts the existing balance of reactants and products.

What is chemical kinetics?

The study of the rates of chemical reactions and the factors affecting these rates.

What is reaction rate?

The speed at which reactants are converted into products in a chemical reaction.

What factors affect reaction rates?

Factors include concentration, temperature, surface area, and the presence of a catalyst.

What is an activated complex?

A temporary, unstable arrangement of atoms during a reaction that leads to product formation.

What is the Arrhenius equation?

An equation that describes how temperature affects the rate of a chemical reaction through the activation energy.

What is the role of reaction mechanisms?

Detailed pathways through which reactants are converted into products, explaining the individual steps in a reaction.

What are intermediates in a reaction?

Species that are produced and consumed during the reaction mechanism, not seen in the overall reaction.

What is the effect of catalysts on reaction rates?

Catalysts lower the activation energy required for a reaction, thereby increasing the reaction rate.

What is the significance of a rate law?

A mathematical expression that relates the reaction rate with the concentrations of reactants.

What does it mean for a reaction to be zero-order?

The rate of reaction is constant and independent of reactant concentration.