Question

What is a homogeneous equilibrium system? Give an example of a homogeneous equilibrium reaction. What is a heterogeneous equilibrium system? Write two chemical equations that represent heterogeneous equilibria.

Short answer

A homogeneous equilibrium system is a chemical reaction where all components are in the same phase, such as the reaction \( N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g) \), where all components are gases. A heterogeneous equilibrium system involves components in different phases, like the reactions \( CO_2(g) + H_2O(l) \rightleftharpoons H_2CO_3(aq) \) and \( CaCO_3(s) \rightleftharpoons CaO(s) + CO_2(g) \), where the reactants and products are a combination of solids, liquids, and gases.

Step-by-step solution

Homogeneous Equilibrium System

A homogeneous equilibrium system is a chemical reaction system where all the components (reactants and products) are in the same phase (state of matter). It means that if the reactants are gases, the products will also be gases, and if reactants are in the aqueous phase, the products will also be in the aqueous phase.

Example of a Homogeneous Equilibrium Reaction

An example of a homogeneous equilibrium reaction is: \( N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g) \) In this reaction, all the components (nitrogen gas, hydrogen gas, and ammonia gas) are in the gaseous phase.

Heterogeneous Equilibrium System

A heterogeneous equilibrium system is a chemical reaction system where the components (reactants and products) are in different phases (states of matter). This means that the reactants and products can be a combination of different phases, such as solids, liquids, and gases.

Examples of Heterogeneous Equilibrium Reactions

Here are two chemical equations that represent heterogeneous equilibria: 1. Carbon dioxide gas dissolving in water to form carbonic acid: \( CO_2(g) + H_2O(l) \rightleftharpoons H_2CO_3(aq) \) In this reaction, carbon dioxide is a gas, water is a liquid, and carbonic acid exists in the aqueous phase. 2. Calcium carbonate decomposing into calcium oxide and carbon dioxide: \( CaCO_3(s) \rightleftharpoons CaO(s) + CO_2(g) \) In this reaction, calcium carbonate and calcium oxide are solids, while carbon dioxide is a gas.

Key concepts

Homogeneous Equilibrium

In chemistry, a homogeneous equilibrium occurs when all the substances involved in a chemical reaction are in the same state of matter. This often happens in reactions where all the reactants and products are gases or all are dissolved in a liquid to form an aqueous solution. Homogeneous equilibria are characterized by a uniform mixture throughout the reaction process, making it easier to predict and calculate the concentrations of all species involved.

For example, consider the formation of ammonia from nitrogen and hydrogen gases:

• Reaction: \( N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g) \)
• All components are in the gaseous state.

Understanding this type of equilibrium is crucial as it plays a significant role in industrial processes like the Haber process, which is used to synthesize ammonia.

Heterogeneous Equilibrium

Heterogeneous equilibrium describes a system where the reactants and products are present in more than one phase. This can be a mixture of solids, liquids, and gases or any combination involving different states of matter. Such equilibria are prevalent in reactions involving solids dissolving in liquids or gases interacting with liquids.

Here are two typical examples:

• A gas dissolving in a liquid, such as carbon dioxide dissolving in water to create carbonic acid:
  • Equation: \( CO_2(g) + H_2O(l) \rightleftharpoons H_2CO_3(aq) \)
  • Involves gas and liquid phases leading to an aqueous product.
• A solid decomposing into a different solid and a gas, such as calcium carbonate breaking down:
  • Equation: \( CaCO_3(s) \rightleftharpoons CaO(s) + CO_2(g) \)
  • Mix of solid and gas phases.

Heterogeneous equilibria are important for understanding natural processes and industrial applications like mineral dissolution and the production of lime.

Equilibrium Reactions

Equilibrium reactions occur when the rate of the forward reaction equals the rate of the reverse reaction, resulting in no net change in the concentrations of reactants and products. At this point, the reaction is at equilibrium, where it appears static, but dynamic molecular activity continues at equal opposing rates. Understanding equilibrium is fundamental in chemistry, as it explains how reactions are balanced and helps in predicting the behavior of reactions under different conditions.

Key features include:

• The reaction can be forward or backward depending on the conditions like temperature and pressure.
• An equilibrium constant \( K \) defines the ratio of product concentrations to reactant concentrations at equilibrium.
• Changes in conditions, according to Le Chatelier's principle, can shift the equilibrium position.

By grasping the concept of equilibrium reactions, chemists can tune reactions for desired outcomes, making equilibrium a pivotal topic in both academic studies and practical applications.