week-10 - Makeup Midquarter Exams Wed., Mar 7 5:30-7:30 pm...

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1 Makeup Midquarter Exams Wed., Mar 7 5:30-7:30 pm 1000 McPherson You MUST have Signed up in 100 CE Final Exams for Chem 122 - Mathews 2:30 Class: Thursday, Mar. 15 at 1:30 (TBA) 6:30 Class: Tuesday, Mar. 13 at 7:30 pm in (TBA) Chapter 17 Additional Aspects of Aqueous Equilibria 17.1 The Common-Ion Effect 17.2 Buffered Solutions Composition and Action of Buffered Solutions Buffer Capacity and pH Addition of Strong Acids or Bases to Buffers 17.3 Acid-Base Titrations Strong Acid-Strong Base Titrations Weak Acid-Strong Base Titrations Titrations of Polyprotic Acids Common Ion Effect : This is the same as other equilibrium calculations, except there is an initial concentration of two species prior to establishing equilibrium. Consider a solution which is prepared by mixing 0.10 mole of acetic acid and 0.010 mole of HCl in enough water to make 1.000 L of solution. What are the concentrations of each species? 1.7x10 -4 0.01 0.10 x 0.01+x 0.10-x eq +x +x -x d 0.01 0.10 I OAc - H 3 O + H 2 O HOAc Note that for a solution of 0.10 M acetic acid alone, [OAc - ] = [H 3 O + ] = 1.3 x 10 -3 M HOAc + H 2 O = H 3 O + + OAc - i 0.30 M ~ 0 0.30 M δ -x x x eq (0.30-x) x (0.30+x) K a = 1.8 x 10 -5 = [(x)(0.30+x)] / [(0.30-x)] leads to x = [H 3 O + ] = 1.8 x 10 -5 M compared to 2.3 x 10 -3 M for the acid alone!!! Consider a solution made from dissolving 0.30 moles of acetic acid and 0.30 moles of sodium acetate in enough water to make 1.00 L of solution. What is the concentration of Hydronium ions and the pH? Consider 1.00L of solution containing 1.00 mol of formic acid (HCOOH) and 0.500 mol of sodium formate (NaHCOO). What is the pH? K a = 1.77 x 10 -4 0.500+x x 1.00-x eq +x +x -x d 0.500 1.00 I A - H 3 O + H 2 O HA 1.77 x 10-4 = (x)(0.500+x) / (1.00-x) (x)(0.500) / (1.00) so x = 3.54 x 10 -4 = [H 3 O + ] and pH = 3.45
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2 Note, however, that we’re doing the same things again! The expression Ka = [H
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This note was uploaded on 07/17/2008 for the course CHEM 122 taught by Professor Zellmer during the Winter '07 term at Ohio State.

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week-10 - Makeup Midquarter Exams Wed., Mar 7 5:30-7:30 pm...

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