2.7 - Solutions and Solubility

• intermolecular interactions needed for dissolving

  intermolecular forces between solute must be overcome

  intermolecular forces between solvent molecules must be overcome

  intermolecular forces between Solvent & solute must be present
• solubility


  measure of the concentration of a saturated solution of a solute at a specified temperature
• saturated solution


  contains as much solute as possible at a particular temperature
• polar solvents


  maude of polar Molecules

  may have hydrogen bonds but always has dipole dipole interactions and London forces
• non-polar solvents


  Made of non-polar molecules

  only have London forces
• non-aqueous solvents


  any solvent other than water
• miscible


  liquids that mix with each other
• immiscible


  liquids that don't mix with each other
• non-polar molecules


  don't dissolve in water because despite separating easily themselves the strong H bands in water act as a barrier so molecules don't mix

  dissolve in non-polar solvents - form London forces
• polar organic molecules


  insoluble in water because despite dipole dipole interactions allowing them to separate they can't form H bonds with water so can't break It bonds in water
• alcohols


  soluble in water because polar -OH bond is attracted to water so H bonds form

  Carbon is hydrophobic so the more carbons the less soluble the alcohol is
• ionic substances


  Soluble in water as ions are attracted to water - energy released when water molecules bind to ions compensates for energy needed to overcome electrostatic force of attraction holding ionic lattice together

  some are insoluble because bonding between their ions is stronger than bonds they could form with Water - eg: AI2O3