#Chem 162-2008 7th week recitation

#Chem 162-2008 7th week recitation - CHEMISTRY 162-2008 7th...

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CHEMISTRY 162-2008 7 th WEEK RECITATION ANNOUNCEMENTS E-MAIL ATTENDANCE Sign in EXAMS QUIZ Chem 162-2008 7 th week recitation 1
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PLAN FOR TODAY : CHAPTER 15 ACIDS AND BASES EQUILIBRIUM Buffers Acid-Base Titrations Indicators Lewis acids and Bases Chem 162-2008 7 th week recitation 2
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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. 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 + Lewis Acid: Anything tending to react with an electron pair, e.g., BF 3 NINE 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- Lewis Base: Anything that has available non-bonding electrons, e.g., NaOH, RNH 2 , CO 3 2- Chem 162-2008 7 th week recitation 3
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ET: First discuss equations, then reverse equations invert K, then Ka x Kb = 10 -14 Write the equil. equations and identify K’s for the following reactions: Weak acid + water (e.g., acetic acid + H 2 O) : HA + H 2 O H 3 O + + A - 1 Assume K a = ~1 x 10 -5 Conjugate base + water (e.g., sodium acetate + H 2 O) : A - + H 2 O HA + OH - 3 K cb = K w /K a = (1 x 10 -14 )/(1 x 10 -5 ) = 1 x 10 -9 Conjugate base + H 3 O + (e.g., sodium acetate + H 3 O + ) :A - + H 3 O + → HA + H 2 O 2 K = 1/K a = 1/(1 x 10 -5 ) = 1 x 10 5 (or bring to completion; then solve for K a ) Weak acid + strong base (e.g., acetic acid + sodium hydroxide) :HA + OH - → H 2 O + A - 4 K = 1/(K w /K a ) = K a /K w = (1 x 10 -5 )/(1 x 10 -14 ) = 1 x 10 9 (or bring to completion; then solve for K a ) Weak base + water (e.g., NH 3 + H 2 O) : RNH 2 + H 2 O RNH 3 + + OH - Assume K b = ~1 x 10 -5 Conjugate acid + water (e.g., sodium acetate + H 2 O) : RNH 3 + + H 2 O RNH 2 + H 3 O + K ca = K w /K b = (1 x 10 -14 )/(1 x 10 -5 ) = (1 x 10 -9 ) Conjugate acid + OH - (e.g., ammonium chloride + OH - ) : RNH 3 + + OH - → RNH 2 + H 2 O K = 1/K b = 1/(1 x 10 -5 ) = 1 x 10 5 (or bring to completion; then solve for K b ) Weak base + strong acid (e.g., NH 3 + H 3 O + ) : RNH 2 + H 3 O + → RNH 3 + + H 2 O K = 1/(K w /K b ) = K b /K w = (1 x 10 -5 )/(1 x 10 -14 ) = 1 x 10 9 (or bring to completion; then solve for K b )
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This note was uploaded on 09/23/2009 for the course CHEM 162 taught by Professor Siegal during the Spring '08 term at Rutgers.

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#Chem 162-2008 7th week recitation - CHEMISTRY 162-2008 7th...

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