Chad provides a comprehensive lesson on buffers and how to do buffer calculations. A buffer is a solution that resists changes in pH and is composed of a weak acid and its conjugate base. Chad discusses at length buffer solution preparation and the related buffer solution preparation calculations. He demonstrates that a buffer can be prepared with the proper ratio of any of the following three mixtures: weak acid / conjugate base, weak acid / strong base, or weak base / strong acid. A weak acid and its conjugate base should be mixed in approximately a 1:1 ratio. A weak acid and strong base should be mixed in approximately a 2:1 ratio. And a weak base and strong acid should be mixed in approximately a 2:1 ratio also. It is also shown that the buffer range is equal to pKa +/- 1, and that polyprotic acids therefore have multiple buffer ranges possible.

pH Calculations with buffers are also demonstrated using the Henderson-Hasselbalch equation. Chad derives the Henderson-Hasselbalch equation from the Ka expression and then uses it to show how to calculate the pH of a buffer solution. Finally, he also shows how to calculate the pH change of a buffer following the addition of strong acid or strong base.

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00:00 Lesson Introduction
00:26 What is a Buffer?
07:12 pKa and Buffer Range
14:47 Buffer Solution Preparation
21:34 Henderson-Hasselbalch Equation Derivation
26:37 How to Calculate the pH of a Buffer Solution
31:03 How to Calculate the Change in pH of a Buffer upon Addition of Strong Acid or Base

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