Buffers

How to make a buffer:

add excess weak acid to strong base - all of NaOH reacted to make salt, but not all CH3COOH is used up

weak acid and its salt

weak base and its salt

Acidic Buffers

CH₃COOH ⇌ CH₃COO^- + H⁺ CH₃COO^- Na⁺ ⇌ CH₃COO^- + Na⁺

acid is added - H+ increases on right side, eqm shifts left to decrease H+ conc.

base added - OH- reacts with H+, decreases H+ conc. eqm shifts right to increase H+ conc.

Basic Buffers

NH₃ + H₂O ⇌ NH₄⁺ + OH^- NH₄Cl ⇌ NH₄⁺ + Cl^-

acid is added - H+ reacts with OH- increasing conc. of H2O, eqm shifts right to decrease OH- conc.

base added - OH- conc. increases, eqm. shifts left to decrease conc.