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Acid-Base and Donor-Acceptor Chemistry

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Presentation on theme: "Acid-Base and Donor-Acceptor Chemistry"— Presentation transcript:

1 Acid-Base and Donor-Acceptor Chemistry
Chapter 6

2 Acids and Bases The Major Acid-Base Definitions:

3 Acids and Bases Arrhenius: Acid is proton source in water, base is hydroxide source Acid + Base = Salt + Water; HCl + NaOH  NaCl + H2O Works in aqueous solutions only Brønsted-Lowry: Acid is proton donor, base is proton acceptor Acid(1) + Base(1)  Acid(2) + Base(2) Can this happen without water? Conjugate acid-base pairs Reaction favors the weaker acid/base pair Non-aqueous solvents, gas and solid phase reactions

4 Acids and Bases Solvent system definition: If a species can autoionize (autodissociate, form a cation and an anion), the cation is an acid and the anion is a base In this system, an acid increases [cation] and a base increases [anion] Water: 2 H2O  H3O+ + OH– HCl is an acid in this solvent system (increases [cation]) HCl + H2O  H3O+ + Cl–

5 Protic Acids and Bases

6 Protic Acids and Bases Kion is K for the autoionization of the pure solvent Solvent Acid Base pKion H2SO4 H3SO4+ HSO4– 3.4 at 10 ºC H2O H3O+ OH– 14 NH3 NH4+ NH2– 27 Acetic acid is acid in water, but base in H2SO4 CH3CO2H + H2SO4  HSO4– + CH3CO2H2+ Urea is a base in water, but an acid in liquid NH3 (NH2)2CO + NH3  NH4+ + (NH2)(NH)CO–

7 Lewis Acid-Base Theory Frontier Orbitals: HOMO and LUMO

8 Lewis Acid vs. Lewis Base vs. Oxidation vs. Reduction

9 Lewis Acid vs. Lewis Base vs. Oxidation vs. Reduction

10 Lewis Acid vs. Lewis Base vs. Oxidation vs. Reduction

11 Lewis Acid vs. Lewis Base vs. Oxidation vs. Reduction

12 Measuring Lewis Acid-Base Interaction Strength via Electronic Spectra

13 Hard and Soft Acids and Bases Examples: Ionic Compound Solubility
AgF(s) + H2O(l)  Ag+(aq) + F-(aq) Ksp = 205 AgCl(s) + H2O(l)  Ag+(aq) + Cl-(aq) Ksp = 1.8 x 10-10 AgBr(s) + H2O(l)  Ag+(aq) + Br-(aq) Ksp = 5.2 x 10-13 AgI(s) + H2O(l)  Ag+(aq) + I-(aq) Ksp = 8.3 x 10-17 Similarly, solubility: Hg2F2 > Hg2Cl2 > Hg2Br2 > Hg2I2 BUT, LiF < LiI MgF2 is less soluble than MgCl2 AlF3 is less soluble than AgCl3

14 Hard and Soft Acids and Bases Examples: Complexation

15 Hard and Soft Acids and Bases Examples: Thiocyanate Bonding to Metals
SCN- can bond through S or N S-binding with M = large, polarizable metals like Hg2+, Au+, Pd2+ N-binding with M = smaller, less polarizable metals: Zn2+, Ni2+

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17 Hard and Soft Acids and Bases Definitions
Hard base: small, not polarizable Soft base: large, highly polarizable

18 Hard and Soft Acids and Bases Definitions
Hard acid: small, not polarizable Soft acid: large, highly polarizable

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25 Relate to oxoanions.

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