1. Acid-base theories Section 15 - 2

2. Objectives Define and recognize Bronsted-Lowry acids and bases. Define a Lewis acid and a Lewis base. Name compounds that are acids under the Lewis definition but are not acids under the Bronsted-Lowry definitions

3. Bronsted-Lowry Acids and Bases Expansion of Arrhenius acid definition Bronsted-Lowry Acid Molecule or ion that is a proton donor HCl + NH3 NH4+ + Cl- H+ is a proton HCl donates H+ (proton) to NH3 H Cl + H N H H N H + Cl H H Bronsted-Lowry Base Molecule or ion that is a proton acceptor NH3 accepts H+ (proton) from HCl Bronsted-Lowry acid-base reaction Protons are transferred from one reactant (the acid) to another (the base) + H _ : : : : : : : : : : : : : : : :

4. Monoprotic and Polyprotic Acids Monoprotic Acid that only donates one proton HCl + H2O H3O++ Cl- Polyprotic Acid that can donate more than one proton per molecule. H2SO4+ H2O H3O+ + HSO4- HSO4-+ H2O H3O+ + SO42- Diprotic and triprotic Obvious!

5. Lewis Acids and Bases Lewis Acid Atom, ion, or molecule that accepts an electron pair to form a covalent bond. Broadest of 3 definitions Lewis Base An atom , ion, or molecule that donates an electron pair to form a covalent bond. Lewis acid-base reaction Formation of one or more covalent bonds between an electron-pair donor and an electron-pair acceptor : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : H H F F F B + N H F B N H F H F H :