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Chem%20162-2011%20Lecture%2010%20truncated

Chem%20162-2011%20Lecture%2010%20truncated - CHEMISTRY...

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Chem 162-2011 Lecture 10 1 CHEMISTRY 162-2011 LECTURE 10 (H&P 15.4-15.5) ANNOUNCEMENTS E-MAIL ATTENDANCE Sign in QUIZ Recitation quiz this week Tue: H&P 14.5-15.3 Fri: H&P 14.5-15.4 EXAMS How did we do? :>)
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Chem 162-2011 Lecture 10 2 PLAN FOR TODAY : CHAPTER 15 (15.4-15.5) ACIDS AND BASES EQUILIBRIUM Equilibrium in Solutions of Weak Acids and Weak Bases Polyprotic Acids
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Chem 162-2011 Lecture 10 3 pH [H + ] 14 Basic 1x10 -14 H 2 O + H 2 O H 3 O + + OH - K w = 1x10 -14 7 Neutral (e.g. H 2 O) 1x10 -7 K w = [H + ][OH - ] = 1 x 10 -14 pH + pOH = 14 K w = K a x K cb = K ca x K b = 1 x 10 -14 * *a & b = acid and base; ca & cb = conjugate acid and conjugate base pK a + pK b = 14 0 Acidic 1x10 o pH’s of 1 to 13 are commonly encountered, but pH’s of -1 or +15 are possible. pH = -log[H + ] pH [H + ] [H + ] = 10 -pH pOH = -log[OH - ] [OH - ] = 10 -pOH pOH [OH - ] pH + pOH = 14 pH + pOH = 14 [H + ][OH - ] = 1 x 10 -14 [H + ][OH - ] = 1 x 10 -14 pOH = -log[OH - ] [OH - ] = 10 -pOH pH = -log[H + ] [H + ] = 10 -pH
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Chem 162-2011 Lecture 10 4 SIX STRONG ACIDS ET: Discuss strong acids and strong bases and the strengths of their conjugate bases and acids; practice both. Very weak base (i.e., not a base; K a Acid spectator ion)** ~10 6 HCl + H 2 O H 3 O + + Cl - ~10 8 HBr + H 2 O H 3 O + + Br - ~10 9 HI + H 2 O H 3 O + + I - H 2 SO 4 + H 2 O H 3 O + + HSO 4 - HNO 3 + H 2 O H 3 O + + NO 3 - HClO 4 + H 2 O H 3 O + + ClO 4 - (HClO 3 + H 2 O H 3 O + + ClO 3 - )* *Strong, but not common acid. Generally not considered as a strong acid. **These conjugate bases are known as “nominal bases”, i.e., a base by definition, but effectively not a base. All other acids are weak acids, e.g., HA (acetic acid), H 2 SO 3 , RNH 3 + , BF 3 Arrhenius acid: Anything that provides a proton, e.g., HA, H 2 SO 3 , RNH 3 + LB Acid: Anything tending to give up a proton, e.g., HA, H 2 SO 3 , RNH 3 + STRONG BASES (Most Group 1A and 2A hydroxides [not HOH]) e.g. Very weak acid (i.e., not an acid; Base spectator ion) LiOH OH - + Li + NaOH OH - + Na + Mg(OH) 2 2OH - + Mg 2+ Ba(OH) 2 2OH - + Ba 2+ All other bases are weak bases, e.g., RNH 2 , CO 3 2- Arrhenius Base: Anything that provides an OH- group, e.g., NaOH LB Base: Anything that tends to react with a proton, e.g., NaOH, RNH 2 , CO 3 2-
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