Lecture 2

8 expand 1 given a pka sketch the t itration curve

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Unformatted text preview: a pKa, sketch the t itration curve. Conjugate Acid OH- Acid dissociation constant Take l og of both sides 1 What is the p Ka o f water? pKa = pH - log( [OH- ]/[H2O] ) ; Rearranged the H-H Eq. Values needed to solve the equation: [Water] is ~55.5 M pH of water is 7, so [OH-] is 1 X 10-7 M 5) Report the buffering range. pKa of water is 15.7! What does the “pKa o f water is 15.7” really mean? Water rarely dissociates to donate a proton. In pure water only 1 in 555,000,000 water molecules is ionized to H+ and OH(55.5 M / 1 X 10-7 M). 1 pKa predicts the leaving group. pKa tells how strongly the acid/base wants the proton The conjugate acid with the lowest pKa H2O vs HCl H+ OH- OH OH C H H Cl- H H H H C C H Cl H H Cl Methanol Methyl Chloride One of the many secrets of life: Turning Bad Leaving Groups into Good Leaving Groups! CO2 Buffering Carbonic Acid What you need to know about pKa Bicarbonate Carbonate H+ H+ HCO3 CO2 + H2 O <-> H2CO3 pKa determines buffering range (pKa ± 1 pH unit) CO3 2 H+ H+ pKa tells how strongly the acid/base wants the proton! pKa predicts what the leaving group will be. (The conjugate acid with the lowest pKa) CO2...
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This note was uploaded on 04/17/2012 for the course BCMB 3100 taught by Professor Mendicino during the Spring '07 term at UGA.

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