Chem 113 1st Edition Lecture 26Outline of Last Lecture I. What makes a base weak?II. Resonance stabilization of (-) chargeIII. Size of an ion: also a delocalization of chargeIV. Electronegativity as a last resortV. Assessing Acidity/BasicityVI. pH and the autoionization of waterOutline of Current Lecture VII. Consequences of KwVIII. The pH ScaleIX. pH, pOH, and pKwX. The Acid Dissociation Constant, KaCurrent LectureI. Consequences of Kwa. At 25°C the [H3O+]x[OH-] always = 1.0x10-14b. A change in [H3O+] causes an inverse change in [OH-] and vice versai. Higher [H3O+] lower [OH-]ii. Higher [OH-] lower [H3O+]c. We can define the terms “acidic” and “basic” in terms of the relative concentrations of H3O+ and OH- ionsi. In an acidic solution, [H3O+]>[OH-]ii. In a neutral solution, [H3O+]=[OH-]iii. In a basic solution, [H3O+]<[OH-]II. The pH Scalea. pH=-log[H3O+]b. The pH of a solution indicates its relative acidityi. In an acidic solution, pH<7.00ii. In a neutral solution, pH=7.00iii. In a basic solution, pH>7.00c. The higher the pH, the lower the [H3O+] and the less acidic the solutionIII. pH, pOH, and pKwThese 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.a. pH=-log[H3O+]b. pOH=-log[OH-]c. pKw=-logKw=14i. pKw=pH+pOH= 14 at 25°CIV. The Acid Dissociation Constant, Kaa. For the equation HA(aq)+H2O(l)H3O+(aq)+A-(aq)i. Kc=Ka=[H3O+][A-]/[HA]b. The value of Ka is an indication of acid strengthi. Stronger acid higher % dissociation of HAlarger Kaii. Weaker acid lower % dissociation of HA smaller
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