Solubility is a key concept in chemistry, influenced by various factors. Temperature and pressure play crucial roles, affecting how substances dissolve in different ways. Understanding these effects helps predict and control solubility in various applications.

Henry's law explains gas solubility in liquids, relating it to pressure. Liquid-liquid solubility ranges from fully miscible to immiscible, depending on molecular properties. These principles are essential for understanding solution behavior and chemical processes.

Factors Affecting Solubility

Temperature and pressure effects on solubility

• Temperature effects on solubility
  • Solids in liquids
    • Generally increases solubility as temperature rises (sugar, salt)
    • Endothermic dissolution process absorbs heat favored by higher temperatures
  • Gases in liquids
    • Decreases solubility as temperature rises (carbonated beverages, oxygen in water)
    • Exothermic dissolution process releases heat favored by lower temperatures
• Pressure effects on solubility
  • Solids and liquids
    • Minimal effect on solubility due to incompressible nature of substances
  • Gases in liquids
    • Increases solubility as pressure rises following Henry's law
    • Gas solubility directly proportional to partial pressure of gas above solution

Henry's law for gas solubility

• Henry's law: $C = k_H \times P$
  • $C$: solubility of gas (mol/L or M)
  • $k_H$: Henry's law constant (mol/L·atm or M/atm) specific to gas-liquid pair at given temperature
  • $P$: partial pressure of gas above solution (atm)
• Calculating gas solubility
  1. Determine Henry's law constant for specific gas-liquid pair at given temperature
  • This constant is related to the solvation process of the gas in the liquid
  1. Identify partial pressure of gas above solution
  2. Multiply Henry's law constant by partial pressure to find solubility

Liquid-Liquid Solubility

Spectrum of liquid-liquid solubility

• Miscibility: ability of liquids to mix forming homogeneous solution
• Fully miscible liquids
  • Completely soluble in each other forming single phase (ethanol and water, acetone and water)
• Partially miscible liquids
  • Soluble in each other to limited extent forming two phases with different compositions (ether and water)
• Immiscible liquids
  • Insoluble in each other forming two distinct phases with no mixing (oil and water, hexane and water)
• Factors affecting miscibility
  • Polarity: similar polarity promotes miscibility
  • Hydrogen bonding: liquids capable of hydrogen bonding more likely to be miscible
  • Temperature: higher temperatures may increase miscibility

Solubility Dynamics

• Saturation: the point at which a solution contains the maximum amount of dissolved solute at a given temperature and pressure
• Dissolution: the process by which a solute dissolves in a solvent to form a solution
• Precipitation: the formation of a solid from a solution when it becomes supersaturated