CHM 104 1st Edition Lecture 16 Outline of Last Lecture I Solutions Containing Bases II Calculating pH III Base Ionization Constant IV Classifying Compounds Outline of Current Lecture V VI VII Mixture of two or more acids Acid Strength Molecular Structure Current Lecture Polyprotic Acid Some acids have 2 or more ionizable protons Ka1 1 6 X 10 2 H2SO3 H2O HSO3 H3O Ka2 6 4 X 10 8 HSO3 H2O SO32 H3O H2A H2O HA H3O Ka1 HA H2O A2 H3O Ka2 Calculate the pH of a 0 100 M oxalic acid H2C2O4 solution Ka1 6 0 X 10 2 Ka2 6 1 X 10 5 H2C2O4 I 0 100 M C E X 0 100 X H2O HC2O4 H3O I 0 0 I X X I X X 6 0 X 10 2 X2 0 100 X X 0 0533 M H3O eq pH 1 27 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 How much extra H3O is coming from HC2O4 HC2O4 I 0 0533 M H2O H3O C2O42 I 0 0533 M 0 C X I X X E 0 0533 X I 0 0533 X X 6 1 X 10 5 0 0533 X X 0 0533 X X 6 1 X 10 5 M H3O Relationship between Ka s and Kb s for polyprotic system A2 H2O HA OH Kb Kw Ka2 HA H20 H2A OH Kb Kw Ka1 Calculate the pH of a 0 100 M sodium oxalate acid Na2C2O4 solution Na2C2O4 s 2 Na aq C2O42 aq C2O42 H2O HC2O4 OH I 0 100 M I 0 0 C X I X X E 0 100 X I X X Kb Kw Ka2 1 0 X 10 14 6 1 X 10 5 1 6 X 10 10 1 6 X 10 10 X2 0 100 X X2 0 100 pOH 5 39 X OH eq 4 0 X 10 6 M pH 8 61 Acid Strength and molecular structure 1 Bond Polarity more polarized stronger the acid 2 Bond Strength more easily broken stronger the acid Binary acids H X Polarity of Bond Strength H F H F 565 KJ mol H Cl H Cl 431 KJ mol Strong C H non polar not an acid H Br 364 KJ mol Acids Oxyacids H O X 1 Electronegativity of X more electronegative stronger the acid of oxygens Ka Perchloric acid HClO4 1 Chloric Acid HClO3 1 Chlorous Acid HClO2 10 2 Hypochlorus Acid HClO 3 X 10 8 Lewis Definition of Acids and Bases Bronsted Acid Donates Proton H Base Accepts Proton Lewis Acid Accepts Electron Pair Base Donates Electron Pair
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