24-acids_bases - Percent Dissociation HA(aq) + H2O(l) H3...

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Unformatted text preview: Percent Dissociation HA(aq) + H2O(l) H3 O+(aq) + A-(aq) % Dissociation = W eek 10 C H E M 1 3 1 0 - S e c tio n s L a n d M [A - ] [HA] x 100 1 Polyprotic Acids Calculate the fractions of H2CO3, HCO3–, and CO32 – at pH 10.00 H 2 CO3 ´ H + (aq) + HCO31- (aq) K a1 = [H + ][HCO3- ] = 4.3x10-7 [H 2 CO3 ] HCO31- (aq) ´ H + (aq) + CO32- (aq) K a2 = [H + ][CO32 - ] = 4.8x10-11 [HCO3- ] Solve on board… W eek 10 C H E M 1 3 1 0 - S e c tio n s L a n d M 2 1 Example Problem Calculate the fractions of H2CO3, HCO3–, and CO32 – at pH 10.00 - K a1 = -7 [HCO3 ] K 4.3x10 [H + ][HCO3- ] = a1 = = 4.3x103 = 4.3x10-7 fi + -10 [H 2 CO3 ] [H 2 CO3 ] [H ] 1.0x10 [H 2 CO3 ] 1 = = 2.3x10-4 3 [HCO3 ] 4.3x10 K a2 = [H + ][CO32 - ] = 4.8x10-11 fi [HCO3- ] W eek 10 [CO32 - ] K 4.8x10-11 = a+2 = = 0.48 [HCO3- ] [H ] 1.0x10-10 C H E M 1 3 1 0 - S e c tio n s L a n d M 3 Fraction of H2CO3 [H 2 CO3 ] 1 = = 2.3x10-4 [HCO3- ] 4.3x103 f ( H 2CO3 ) = [CO32 - ] K 4.8x10-11 = a+2 = = 0.48 [HCO3 ] [H ] 1.0x10-10 [ H 2CO3 ] [ H 2CO3 ] + [ HCO3- ] + [CO32- ] [ H 2CO3 ] [ HCO3- ] f ( H 2CO3 ) = [ H 2CO3 ] [ HCO3- ] [CO32- ] + + [ HCO3- ] [ HCO3- ] [ HCO3- ] f ( H 2CO3 )= W eek 10 2.3 x 10-4 = 1.6x10-4 2.3 x 10-4 + 1 + 0.48 C H E M 1 3 1 0 - S e c tio n s L a n d M 4 2 Fraction of HCO3[CO32 - ] K 4.8x10-11 = a+2 = = 0.48 [HCO3- ] [H ] 1.0x10-10 f ( HCO3- ) = [H 2 CO3 ] 1 = = 2.3x10-4 [HCO3- ] 4.3x103 [ HCO3- ] [ H 2CO3 ] + [ HCO3- ] + [CO32- ] [ HCO3- ] [ HCO3- ] f ( HCO3- ) = [ H 2CO3 ] [ HCO3- ] [CO32- ] + + [ HCO3- ] [ HCO3- ] [ HCO3- ] f ( HCO3- )= W eek 10 1 = 0.68 2.3 x 10 + 1 + 0.48 -4 C H E M 1 3 1 0 - S e c tio n s L a n d M 5 Fraction of CO32Calculate the fractions of H2CO3, HCO3–, and CO32 – at pH 10.00 f (CO32- ) = [CO32- ] [ H 2CO3 ] + [ HCO3- ] + [CO32- ] [CO32- ] [ HCO3- ] f (CO32- ) = [ H 2CO3 ] [ HCO3- ] [CO32- ] + + [ HCO3- ] [ HCO3- ] [ HCO3- ] f (CO32- )= W eek 10 [CO32 - ] K 4.8x10-11 = a+2 = = 0.48 [HCO3 ] [H ] 1.0x10-10 [H 2 CO3 ] 1 = = 2.3x10-4 [HCO3- ] 4.3x103 0.48 = 0.32 2.3 x 10-4 + 1 + 0.48 C H E M 1 3 1 0 - S e c tio n s L a n d M 6 3 Ch 7: Acids & Bases Study Sections 7.1 - 7.8 and 7.11 Be able to define and ID Arrhenius acids/bases and Bronsted-Lowry acids/bases Define Ka or Kb and perform pH calculations for strong or weak acids/bases Acid or base strength Handling polyprotic acids Percent dissociation calculations W eek 10 C H E M 1 3 1 0 - S e c tio n s L a n d M 7 W eek 10 C H E M 1 3 1 0 - S e c tio n s L a n d M 8 4 ...
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This note was uploaded on 08/23/2011 for the course CHEM 1310 taught by Professor Staff during the Spring '11 term at University of Florida.

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