CHEM 1415 1st EditionLecture 18Unit: Acids and BasesOutline of Current Lecture I. Bronsted-Lowry DefinitionII. Conjugate acid-base pairsIII. Example Problem 1IV. Free Energy and Chemical EquilibriumCurrent Lecture Bronsted – Lowry definition – an acid is a proton +¿H¿¿ donor and a base is a proton acceptoro water can act as both an acid or a base, depending on the properties of the othersubstanceo amphoteric – refers to any substance that can be either an acid or a base Conjugate acid-base pairs o Conjugate acid – of a base is the acid formed when the base receives a protono Conjugate base – of an acid is the base formed when the acid gives a protono pH = +¿H3O¿−log ¿ Example Problem 1: The Kaof acetic acidC H3COOH ,is 1.8∗10−5. what is the pH of a 0.10 M solution.−¿(aq)+¿(aq)+C H3COO¿C H3COOH(aq)+H2O(l)← H3O¿C H3COOH(aq)+¿(aq)H3O¿−¿(aq)C H3CO O¿Initial concentration0.10 0 0Change in Concentration-x +x +xFinal 0.10 – x X XThese 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.Concentration+¿H3O¿¿−¿C H3CO O¿¿¿Ka=¿x2=1.8∗10−5(0.10)=1.8∗10−6x=1.3∗10−3MpH=−log(1.3∗10−3)=2.9 Free Energy and Chemical Equilibriumo Equilibrium – a state of minimum free energyo Free energy decreases as you move toward equilibrium from either directiono Chemical systems tend to move spontaneously toward equilibriumo∆ G=∆
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