AcidBase Equilibria Currituck County Schools酸碱平衡柯里塔克县学校.pptVIP

Acid-Base Equilibria Arrhenius acids increase [H+] when dissolved in water acids can be classified as monoprotic, diprotic or triprotic bases increase [OH-] when dissolved in water bases can be classified as monobasic, dibasic, or tribasic A-B Strength strong acids bases ionize completely and are strong electrolytes 7 acids 8 bases (memorize them!!!) diprotic acids dibasic bases do NOT ionize completely, only their first H+ or OH- ionizes completely. Strong acid + strong base = neutral salt strong A-B are not equilibrium expressions, but all other A-B are reversible Bronsted-Lowry A-B restricts definition to H+ acids donate H+ bases accept H+ allows the classification of less traditional A-B conjugate A-B pairs = 2 formulas in an equation whose formulas differ by a H+ What is the acid, base, and the conjugates? HClO +H2O H3O+ + ClO- CO32- + H2O OH- + HCO3- Wait, water can go both ways? amphoteric substances can behave as either an acid or base depending on what they react with. water and anions with protons (H+) attached are most common amphoterics Lewis A-B Theory very general definition of A-B using electron pairs acid = electron pair acceptor base = electron pair donor In the following equation, which species acts as a Lewis acid and which acts as a base? BF3 + NH3 BF3NH3 Weak A-B only partially ionize in water and are weak electrolytes can be written as equilibrium expressions with a Ka or Kb value K value indicates how much the acid or base will ionize (high K = higher ionization) larger K values indicate a stronger acid or base For di- and tri- protic/basic, there will be 2 K values (one for the first ionization and one for the second) Autoionization of Water H2O + H2O OH- + H3O+ reversible equilibrium where water can donate a proton to itself Kw = 1.0 x 10-14 at room temp. For any conjugate A-B pair, Kw = Ka x Kb What is the Ka value for NH4+? Example Is an aqueous solution of Na2HPO4 acidic or basic? pH scale pH = -log[H+] works for pH rang