Structure and Properties of Water Compound Molecular weight (Da) Melting point (°C) Boiling point (°C) Methane 16.04 -182.6 -161.4 Ammonia 17.03 -77.7 -33.35 Water 18.02 0 100 Methanol 32.04 -93.9 64.7 !"" !"bb#"b# !""!""!""!""!"" Ionic interactions ! F =kq1q2"r2 k = 8.99 x 109 J•m/C2 q1 & q2 = charge r = distance ε = dielectric constantSolute ∆Hsolute ∆Ssolute ∆Hwater ∆Swater Ion Hydration Spheres Chloride SodiumSolute ∆Hsolute ∆Ssolute ∆Hwater ∆Swater Polar Solute ∆Hsolute ∆Ssolute ∆Hwater ∆Swater Non-polar Clathrate –Hydrophobic effect – ! V =43"r3 ! A = 4"r2 Amphipathic molecules – O O Critical Micellar Concentration (CMC) – O O O P O O O N + C H 3 C H 3 C H 3 O ODissociation of water OHH2OH+ K =[ H+][OH–][H2O] Strong Acids – Weak acids – ! K =[H3O+][A–][HA][H2O] ! K [H2O] = Ka=[H3O+][A–][HA] ! [H3O+] = Ka[HA][A–] ! pH = pKa" log[HA][A–] ! pH = pKa+ log[A–][HA]
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