4.7 Kw and the Ionization of Water Chemistry 12 http://www.800mainstreet.com/acid_base/dissociation_of_water.html

2 H2O(l) + 59J ↔ H3O+(aq) + OH−(aq) 4.7 2 H2O(l) + 59J ↔ H3O+(aq) + OH−(aq) Spontaneous Not very often Affected by temperature

2 H2O(l) + 59J ↔ H3O+(aq) + OH− (aq) 4.7 2 H2O(l) + 59J ↔ H3O+(aq) + OH− (aq) Kw expression and value? Pure liquids (and solids) left out of Keq Kw = [H3O+][OH−]

4.7 Kw value? Kw = 1.0×10−14 At 250C p.334

2 H2O(l) + 59J ↔ H3O+ (aq) + OH− (aq) 4.7 What happens to the value of Kw if the temperature of H2O is increased above 250C? 2 H2O(l) + 59J ↔ H3O+ (aq) + OH− (aq) Increased temperature is a stress  according to LCP, shift will be away from heat term [H3O+] and[OH−] will increase KW will increase

4.7 What is the [H3O+] of pure water at 250C? Kw = [H3O+][OH−] = 1.0×10−14 [H3O+] = [OH−] [H3O+]2 = 1.0×10−14 [H3O+] = 1.0×10−14 = 1.0×10−7

Learning Check What is the ionization of water? How do the [H3O+] and [OH-] compare in acidic, basic and neutral conditions? What is Kw and how is it affected by temperature? What is the value of Kw at 25C? Can you calculate [H3O+] or [OH-] at 25C using Kw?

Read & Highlight Self Notes (p.1-2) Homework Hebden #28, 29 4.7 Read & Highlight Self Notes (p.1-2) Homework Hebden #28, 29