LECTURE15 - Midterm 2 Friday May 13th In class. Henrys law...

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1 Midterm 2 Friday May 13 th In class. Henry’s law + Colligative properties (chap 13) Equilibrium (chap 14) Acids and Bases (chap 15) More Acids and Bases (chap 16) More information later… Last Time: pH Strong acid or base: Weak acid or base: pH = -log 10 [H 3 O + ] = -log 10 [HCl] initial HCl(aq) + H 2 O(l) H 3 O + (aq) + Cl (aq) HC 2 H 3 O 2 (aq) + H 2 O(l) H 3 O + (aq) + C 2 H 3 O 2 (aq) K a = [CH 3 CO 2 H] [CH 3 CO 2 ][H 3 O + ] equilibrium/ICE table! 2H 2 O(l) H 3 O + (aq) + OH (aq) K w =[H 3 O + ][OH ] Very dilute strong acid or base e.g. 1 nM HNO3 (last class):
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2 What is the pH of a 4.5 x 10 –8 M solution of ammonia? pK b =4.74 pH Dilute Weak base 2H 2 O H 3 O + + OH xx NH 3 + H 2 O NH 4 + + OH 4.5x10 -8 –y y y [H 3 O + ] = x [OH ] = y+x [NH 4 + ] = y [NH 3 ] = 4.5x10 -8 –y K w =[H 3 O + ][OH ] = x (y + x) = 1x10 -14 K b = [NH 3 ] [NH 4 + ][OH ] = 1.8 10 -5 = 4.5x10 -8 –y y(y+x) 1… 2… , x = [H 3 O + ] = 8.01x10 -8 pH = 7.1 y = 4.47x10 -8 Equil: Equil: K b = 10 -4.74 = 1.8 10 -5 Degree of Ionization HA + H 2 O H 3 O + + A - Degree of ionization = [H 3 O + ] from HA [HA] originally Percent ionization = [H 3 O + ] from HA [HA] originally 100% K a = [H
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This note was uploaded on 07/09/2011 for the course CHE 2B 2B taught by Professor Tobyallen during the Spring '11 term at UC Davis.

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LECTURE15 - Midterm 2 Friday May 13th In class. Henrys law...

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