Keywords: Raoult’s Law, vapor pressure, ideal solution, non-ideal solution, mole fraction, chemical equilibrium
🔬 Basic Concept
Raoult’s Law is a key principle in chemistry that helps predict the vapor pressure of a solution. It applies strictly to ideal solutions, where intermolecular forces are similar throughout. The law connects the mole fraction of a component to its partial vapor pressure in the solution.
💡 Definition
Raoult’s Law can be expressed as:
$$
P_A = X_A \cdot P_A^0
$$
where:
- $P_A$ : partial vapor pressure of component A in the solution
- $X_A$ : mole fraction of component A in the solution
- $P_A^0$ : vapor pressure of pure component A
🌍 Non-Ideal Solutions and Limitations
In practice, not all solutions behave ideally. In non-ideal solutions, the intermolecular forces differ from those in ideal solutions, leading to deviations from Raoult’s Law. In such cases, chemists often use activity coefficients or apply Henry’s Law for more accurate predictions.
⚗️ Applications
- Distillation: separating mixtures
- Calculating vapor pressure of solutions
- Understanding phase diagrams and boiling point elevation
Raoult’s Law remains a cornerstone of solution chemistry, bridging theoretical concepts with practical industrial and laboratory applications.