CHEM211 Lecture Notes - Lecture 35: Transition Metal, Analyte, Coordination Complex
23 Dec 2017
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Weak bases: a- or b hydrolyzes with small equilibrium constant. B+h20 bh+ + oh- or a- + h20 ha + oh- Kb = [bh][oh-]/[b] or kb = [ha][oh-]/[a-] Ka x kb = kw. (kw = 1. 00 x10^-14) Weak acid ka << 1, weak base kb << 1. Typical weak acids (carboxylic acids (rooh), protonated amines (r3nh+), inorganic ions (hpo4 2-, h2po4-, hso4-, hco3-) Typical weak bases (carboxylic anions rcoo-), amines (r3n), inorganic ions (po4 3-, hpo4 3-, H2 po4-, so4 2-, co3 2-, hco3 -) Fractional composition (a) = fraction of specific form of a molecule of all forms of a molecule. Aa- fraction of dissociation = fraction of acid that is in the form a-. Buffers; solutions which resist change in ph when acid or base is added or dilution occurs. Buffers in ph range 3-11 are mixtures of a weak acid and its conjugage base. H-h equation; ph = pka + log ([a-]/[ha]).
