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4.7 Kw and the Ionization of Water. Chemistry 12 http://www.800mainstreet.com/acid_base/dissociation_of_water.html. 4.7. 2 H 2 O (l) + 59J ↔ H 3 O + (aq) + OH − (aq) Spontaneous Not very often Affected by temperature. 4.7. 2 H 2 O (l) + 59J ↔ H 3 O + (aq) + OH − (aq)
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4.7 Kw and the Ionization of Water Chemistry 12 http://www.800mainstreet.com/acid_base/dissociation_of_water.html
4.7 2 H2O(l) + 59J ↔ H3O+(aq) + OH−(aq) Spontaneous Not very often Affected by temperature
4.7 2 H2O(l) + 59J ↔ H3O+(aq) + OH−(aq) Kwexpression and value? Pure liquids (and solids) left out of Keq Kw = [H3O+][OH−]
4.7 At 250C p.334 Kw value? Kw = 1.0×10−14
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 25C? Can you calculate [H3O+] or [OH-] at 25C using Kw?
4.7 Read & Highlight Self Notes (p.1-2) Homework Hebden #28, 29