Acid-Base Equilibria

Buffer Solution Active Learning Instructional Sequence Part 1

Different size tablets of Alka-Seltzer™ dissolved in water will neutralize different amounts of acid and base.

Buffer solution pH Computer Simulation measure the pH of various solutions created by mixing a weak acid (i.e. acetic acid) with the salt of the weak acid (i.e. sodium acetate).

The initial pH of an acetic acid/sodium acetate buffer solution is compared to the pH of deionized water. Universal indicator solutions is used to show the initial pH of both solutions are around 7.0. When small quantities of hydrochloric acid and sodium hydroxide are added to each solution, the buffer solution resists the change in pH while the pH of water changes dramatically - decreases with the addition of a small amount of HCl(aq) or increases with the addition of a small amount of NaOH(aq).

Acid and base added to buffers of various concentrations to show capacity and how it is affected.

When soluble ioinc salts are dissoved in water the pH changes due an increase or decrease of hydronium ions, plus oher ions. Hydronium ions generated or consumed by the conjuate acid-base pairs, cause the pH to change and cuase a corresponding acid-base indicator color change.