State Henry’s Law. Write four conditions for ideal solutions.

Answer:

Henry’s law: The solubility of a gas in a liquid at constant temperature is directly proportional to the pressure of the gas above the solution. S = K_HP, where S is the solubility (mol L⁻¹), P the pressure of the gas and K_H the Henry’s law constant.

Conditions for an ideal solution:

1. It obeys Raoult’s law over the entire range of concentrations.
2. Enthalpy of mixing is zero: Δ_mixH = 0 (no heat is absorbed or evolved).
3. Volume of mixing is zero: Δ_mixV = 0 (volume of solution = sum of volumes of the components).
4. Solute–solvent (A–B) intermolecular forces are of the same strength as the A–A and B–B forces.