Qwiki

Acid-Base Titration

Acid-base titration is a fundamental analytical technique in chemistry used to determine the concentration of an unknown acid or base solution. This process involves the gradual addition of a solution of known concentration, called the titrant, to a solution of unknown concentration until the reaction reaches the equivalence point.

Principles of Acid-Base Titration

The principle behind acid-base titration is the neutralization reaction, where an acid reacts with a base to form water and a salt. This reaction can be described by the general equation:

[ \text{Acid} + \text{Base} \rightarrow \text{Salt} + \text{Water} ]

Types of Acid-Base Reactions

  1. Brønsted-Lowry Acid-Base Reactions: This theory defines acids as proton donors and bases as proton acceptors. The neutralization involves the transfer of protons (H⁺ ions).

  2. Lewis Acid-Base Reactions: In these reactions, a Lewis acid is a species that can accept a pair of electrons, while a Lewis base can donate a pair of electrons.

Titration Curves and Indicators

A key aspect of acid-base titration is monitoring the pH change, which is plotted on a titration curve. The curve typically shows a sharp change at the equivalence point, where the amount of acid equals the amount of base.

pH Indicators

To detect the equivalence point, a pH indicator is often used. Common indicators include:

Procedure of Acid-Base Titration

  1. Preparation: A known volume of the sample (acid or base) is placed in a flask. A few drops of a suitable indicator are added.

  2. Titration: The titrant is slowly added from a burette to the flask while continuously stirring the solution until the endpoint is reached, as indicated by a sustained color change.

  3. Calculation: The volume of titrant used is recorded. Using the balanced equation of the reaction, the concentration of the unknown solution can be calculated.

Applications of Acid-Base Titration

Acid-base titration is widely used in various fields such as:

  • Pharmaceuticals: For determining the concentration of drugs.
  • Food industry: To measure the acidity of food products.
  • Environmental science: To analyze the acidity or alkalinity of water bodies.

Related Topics