π What is Homogeneous Equilibrium?
Homogeneous equilibrium refers to a state of equilibrium where all the reactants and products are in the same phase. This means everything is either a gas, liquid, or solid. No phase boundaries exist within the system.
π§ͺ What is Heterogeneous Equilibrium?
Heterogeneous equilibrium, on the other hand, occurs when the reactants and products are present in different phases. This means you might have solids reacting with gases, or liquids mixing with solids, creating distinct phase boundaries.
π Homogeneous vs. Heterogeneous Equilibrium: A Detailed Comparison
| Feature |
Homogeneous Equilibrium |
Heterogeneous Equilibrium |
| Definition |
All reactants and products are in the same phase. |
Reactants and products exist in multiple phases. |
| Phase Boundaries |
No phase boundaries exist. |
Distinct phase boundaries are present. |
| Examples |
$N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)$ |
$CaCO_3(s) \rightleftharpoons CaO(s) + CO_2(g)$ |
| Equilibrium Constant Expression |
Includes all reactants and products. |
Pure solids and liquids are excluded (their activities are considered 1). |
| Complexity |
Generally simpler to analyze. |
Can be more complex due to phase considerations. |
π Key Takeaways
- π Phase Matters: The key difference is whether all components are in the same phase (homogeneous) or in different phases (heterogeneous).
- π Equilibrium Constant: Remember to exclude pure solids and liquids when writing the equilibrium constant expression for heterogeneous reactions.
- π‘ Real-World Relevance: Many industrial processes involve heterogeneous catalysis, where reactants in one phase react on the surface of a solid catalyst. Understanding heterogeneous equilibrium is crucial in these scenarios.
- π§ͺ Example Homogeneous: The Haber-Bosch process ($N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)$) is a classic example of homogeneous equilibrium.
- π Example Heterogeneous: The decomposition of calcium carbonate ($CaCO_3(s) \rightleftharpoons CaO(s) + CO_2(g)$) is a common example of heterogeneous equilibrium.