pKa handout

pKa handout - ] [HA] logK a = log[H + ]+ log [A ] [HA] logK...

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Biological Sciences 102 Spring 200 8 Handout C lass AB Prof R Holland Cheng http://pioms.ucdavis.edu/ Classes of acid/base problems Four Classes of acid/base problems Class 1: "Acid” form only Class 2: "Base” form only Class 3: "Acid" plus "Base" forms Class 4: Polyprotic acids - amphoteric substances Short list of equations discussed HA H + + A - K a = [H + ][A ] [HA] A - + H 2 O HA + OH - K b = [HA][OH - ] [A - ] K w = K eq [H 2 O] = [H + ][OH - ] = 10 -14 pK b = 14 – pK a Henderson-Hasselbalch Equation K a = [H + ][A ] [HA] logK a = log [H + ][A
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Unformatted text preview: ] [HA] logK a = log[H + ]+ log [A ] [HA] logK a = log[H + ] log [A ] [HA] pK a = pH log [A ] [HA] pH = pK a + log [A ] [HA] Polyprotic acid A simplified way is to consider when one molecule of HA-dissociates to give an H + , another molecule of HA-can pick it up to give H 2 A: HA- H + + A 2-K eq = K a2 H + + HA- H 2 A K eq = 1/K a1 Net reaction: 2HA- H 2 A + A 2-K eq = K a2 /K a1 pH = pK a1 + pK a2 2...
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This note was uploaded on 02/21/2009 for the course BIS 102 taught by Professor Hilt during the Spring '08 term at UC Davis.

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