# Acid/ Base Definitions - Lompoc Unified School District Acid/ Base Definitions Arrhenius Definitions Acid H+/H3O+ producer Base OH- producer

Good for strong acids and bases Bronsted-Lowry Definition Acid proton (H+) donor

Base proton acceptor Accounts for some weak bases which do not have an OH- Lewis Definition Acid electron pair acceptor

Base electron pair donor Encompasses even more than the Bronsted-Lowry definition Identify the Lewis acid and base Ni2+ + 6NH3 Ni(NH3)62+ H+ + H2O H3O+ Conjugate Acid/Base

In every acid/base reaction, there are actually two acids and two bases NH3 + HF F- + NH4+ On the reactant side, HF is an acid so it has a Ka, but on the product side F- the is a base so it has a Kb

Relationship Between Ka and Kb Ka x Kb = Kw pK = - log K

pKa + pKb = 14.00 Example Calculate the Kb for the F- ion if the Ka for its conjugate acid is given in Appendix A5.1.

Calculate the Ka for the ammonium ion, NH4+. Example Calculate the pH of a .30M NaF solution.

The Ka for HF is 7.2x10-4.