F BICH 410 1st Edition Lecture 2 Outline of Last Lecture Covalent Bonds Noncovalent bonds Water and the importance of Hydrogen bonds Outline of Current Lecture Ka ionized constant or weak acid in awater o logKa Pka o Smaller pka stronger weak acid o Larger Ka stronger weak base pH determined by both pka of conjugate acid base pair and the conc of conjugate acid base pair pH pka log deprotanated protonated Henderson Hasselbach o charged form could be protonated or deprotonated When pH Pka A HA When Ph Pka larger pka less likely to dissociate When pH Pka smaller pka more likely to dissociate more deprotonated Titration Curves adding strong base to weak acid and measuring change in Ph o Graph pH v amount of strong base added o Inflection point acid base These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute o Should be able to determine pka and which form will predominate ie acid or base as a certain spot on graph Bio Systems Buffered o Buffers resist changes in PH as acid and base are added o Titration curve near pka is buffer o The greater the conc of weak acid and its conj base the greater the buffer capacite o Find good buffer by matching desired pH with matching pka of buffer Major Bio Buffers o H2PO4 H2PO42 The principle buffer in cells pka 7 o H2CO3 HCO3 Important buffer in the blood CO2 H20 H HCO3 CO2 HA HCO3 A Changes in Blood Chemistry o Breathing induced CO2 H20 H HCO3 Hyperventilation result in increased blood pH CO2 down so body pushes rxn to the left causing HCO3 to decrease So pH increases because H decreases respiratory alkalosis Hypoventilation results in decreased blood pH Increase in CO2 combines with H20 to produce more H so pH decreases respiratory acidosis o Metabolically induced Decreases in blood pH result increases breathing rate pH decreases H increases so H combines w HCO3 to produce more CO2 metabolic acidosis Increase in blood pH very rare decreases breathing rate pH increases or H decreases CO2 combines w H20 metabolic alkalosis Thermodynamics Kinetics Equilibrium o Thermodyamics are products possible spontaneous v non favorable v non o Kinetics expresses how fast process occurs o Equilibrium how far rxn will go State in which forward rxn reverse rxn Conc of reactants and products remain constant over time but not equal dynamic process All chem rxn proceed until equilibrium reached Equilibrium level for a rxn is intrinsic to each specific rxn Le Chateliers any stress placed on equilibrium system will cause the system to shift to minimize effect of stress Equilibrium constant keq Products x Reactants x Change temp causes change in keq Keq 1 more reactants Keq 1 products predominate
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