Chemistry of Water

I.        Basis for Properties

          A.       structure

          B.       Interaction between molecules

II.       Oddball Compound

          A.       State

          B.       Melting point

          C.       Boiling point

          D.       Density change

III.      Structure

          A.       Large DEN

          B.       2 shared and 2 unshared pairs

          C.       Bent pyramid

          D.       Polar

IV.      Hydrogen Bonding (h-bond_

          A.       More electronegative element pulls electrons

          B.       H nucleus is exposed

          C.       H attracted to unshared pairs

          D.       Forms from H-O, H-N, or H-F bond

          E.       H₂O forms 4

V.       Effect on State

          A.       Depends on balance between KE and cohesive force

          B.       H-bond add to cohesive force

          C.       Higher MP and BP

VI.      Effect on Density

          A.       Most solids more dense

          B.       H-bond pulls H₂O closer as it cools

          C.       At 4ºC H-bond causes move to hexagon

          D.       This is most stable solid structure

VII.     Effect on Surface Tension

          A.       Force needed to break surface of liquid

          B.       Net inward force at surface

                     1.       Cohesive force

                     2.       H-bond

          C.       Shape of material dependent on surface tension

          D.       Strength of surface dependent on surface tension

VIII.    Effect on Capillarity

          A.       Liquid rises in tube

          B.       Interaction between intermolecular forces in liquid and adhesive forces of tube

          C.       H₂O forms H-bond with O₂ in glass of tube

          D.       H₂O pulled up tube

IX.      Effect of Specific Heat

          A.       Energy needed to raise temperature by 1K

          B.       H-bond absorbs some NRG as PE

          C.       More needed to raise KE (temperature)

X.       Effect on Solution Process

          A.       H-bond produces polarity

          B.       Polar molecules pulls solute into solvent

XI.      Solution

          A.       Homogeneous mixture of molecules

          B.       Solvent surrounds solute

XII.     Dissolving Process

          A.       Solvent molecules pull solute into pieces

          B.       Solvent surrounds solute

          C.       Dispersion of solvent spread solute

XIII.    Dissolving Process: Ionic

          A.       Ions dissociate

          B.       Ion-dipole interaction pulls O to positive pole

          C.       Ion-dipole interaction pulls H to negative pole

          D.       Ions are surrounded and disperse with H₂O

XIV.    Dissolving Process: Covalent

          A.       Molecules have polar O-H bonds

          B.       H₂O molecules attracted to polar bond

          C.       H₂O surrounds and pulls individual molecules

          D.       Molecules disperse with H₂O

XV.     Like Dissolves Like

          A.       Most likely when solvent and solute similar

          B.       Ionic and Polar dissolve Ionic

          C.       Covalent dissolves covalent

XVI.    Concentration

          A.       Dilute: a small amount of solute

          B.       Concentrated: a large amount of solute

          C.       Unsaturated: < the max amount of solute

                     1.       Amount depends on temperature

          D.       Saturated: the max amount of solute

          E.       Molarity: Moles / Liter

XVII.   Heat of Solution

          A.       Energy required to dissolve

          B.       Most endothermic

XVIII.  Colligative Properties

          A.       Depend on moles present

          B.       Independent of nature of mature

          C.       Non-volatile

          D.       Ionic solutes dissociate to produce more particles

XIX.    Freezing

          A.       Molecules must be free to form crystal

          B.       Solute molecules block movement

          C.       Depression Constant

                     1.       Property of solvent

                     2.       Depression per mole of solute

                     3.       H₂O: 1.86K/mol

XX.     Boiling

          A.       Molecules must be free to leave liquid

          B.       Solute particles block movement out of liquid

          C.       Vapor pressure lowers (must equal atmospheric pressure for boiling)

          D.       More KE needed

          E.       Elevation Constant

                     1.       Elevation per mole of solute

                     2.       0.5K/mol

XXI.    Osmosis

          A.       Flow of H₂O across membrane

          B.       From high H₂O concentration to low

          C.       Continues to equilibrium

          D.       Isotonic

          E.       Hypotonic

          F.       Hypertonic