Question

Explain Raoult's Law.

Hint:

Raoult's Law is fundamental in studying solutions. Remember that it applies strictly to ideal solutions, while real solutions show positive or negative deviations depending on intermolecular forces.

Answer 1

Raoult's Law states that the partial vapor pressure of a component in a liquid solution is directly proportional to its mole fraction in the solution. \[ p_A = \chi_A \cdot p_A^0 \] Where:
- \( p_A \) = partial vapor pressure of component A in solution,
- \( \chi_A \) = mole fraction of component A in solution,
- \( p_A^0 \) = vapor pressure of pure component A.
For a binary solution (components A and B), the total vapor pressure is: \[ p_{\text{total}} = p_A + p_B = \chi_A p_A^0 + \chi_B p_B^0 \] Significance: - Raoult's Law helps in understanding colligative properties like relative lowering of vapor pressure, elevation of boiling point, depression of freezing point, and osmotic pressure.
- It is valid for ideal solutions where intermolecular interactions between unlike molecules are similar to those between like molecules.