TYPE 1 (conj. BASE of weak acid)( only the SALT of a weak acid put in solution )For a salt of a weak acid (NaA) in water:STEP 1:NaA (s) + H2O Na++ A-(100% ionization!!!)STEP 2:A-+ H2O HA + OH-Note that A- behaves EXACTLY like a weak base in water (a Type 1 problem for bases) and the equilibria isKb-OHHAA=-and remember Kbfor A-must be calculated from Kafor HA: KKKbwa=Now let CA-be the analytical concentration (label) of the conjugate base, A- :Our Equilibrium "Chart"[A-][OH-][HA]initialCA-00change-x+x+xfinalCA-- xxxKxxb2AC-=-(29Equation 3.1KCK xxbAb--=()202=+-xKbbAC-OHA4CbbbA---===-++xKKK22This equation is the exact solution for calculating the [OH-] for any solution made by mixing a concentration of
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This note was uploaded on 11/02/2008 for the course CH 301 taught by Professor Fakhreddine/lyon during the Fall '07 term at University of Texas.