L31 - Acids and Bases

Experimental determination of an acid/base concentration in solution by using the technique of titration

Titration

A technique used to determine the concentration of an acid or its equilibrium constant by adding a base, or vice versa.

Strong acids and bases

Acids and bases that fully dissociate in water, or are so close to complete dissociation it can be assumed.

Weak acids or weak bases

Require the use of the equilibrium constant and ICE method to calculate the H3O+ concentration.

Buffer solutions

Solutions that contain both an acid and its conjugate base, resisting changes in pH.

Henderson-Hasselbalch equation

pH = pKa + log([Base]/[Acid])

Acid-base indicators

Weak acids which undergo a change in color when deprotonated, useful for visualizing pH changes.

Equivalence point

The point in a titration where the moles of added acid equal the moles of base, or vice versa.

Endpoint

The point in a titration where the indicator changes color.

Titrant

The substance added from a burette in a titration, usually a strong acid or base.

pH at Equivalence Point of Strong Acid and Strong Base

pH = 7

pH at Equivalence Point of Strong Base and Weak Acid

pH > 7

pH at Equivalence Point of Strong Acid and Weak Base

pH < 7

Initial pH of Weak Acid

Use ICE method to determine the initial pH

Half Equivalence Point

The point at which half the volume of strong base needed to reach the equivalence point has been added; pH = pKa