Steps in Solvation Endothermic- Exothermic- energy energy absorbing releasing Dissociation Dissociation of Ionic Dissociation of Compounds Covalent Compounds Electrolytes • When ionic compounds battery bulb + dissociate and a charge if applied to the solutions Na+ + - Cl- deionized water + NaCl When Electrolytes are Acids •Examples: • HCl(aq) --> H+(aq) + Cl-(aq) • HNO3(aq) --> H+(aq) + NO3-(aq) •Acids like HCl and HNO3 are called MONOPROTIC acids since every molecule of HCl or HNO3 produces one H+ •Acids like HCl and HNO3 completely dissociate in water •These acids are are STRONG ACIDS, and hence also strong electrolytes Colligative Properties Depend only on the number, not on the identity, of the solute particles in an ideal solution. Boiling point elevation Freezing point depression Osmotic pressure Osmotic Pressure Osmosis: The flow of solvent into the solution through the semipermeable membrane. Osmotic Pressure: The excess hydrostatic pressure on the solution compared to the pure solvent. Precipitation Reactions 2 KI(aq) + Pb(NO3)2(aq) --> PbI2 (s) + 2 KNO3 (aq) The reaction between the KI and Pb(NO3)2 results in the formation of PbI2 which has a very low solubility in water and forms a solid precipitate. 2 KI(aq) + Pb(NO3)2(aq) --> PbI2 (s) + 2 KNO3 (aq) For compounds insoluble in water, the attraction between the oppositely charged ions in the solid crystal are too strong to be overcome by solvent water molecules. KNO3, being soluble in water, exists in solution as K+ and NO3- ions.