it is a substance which changes its smell depending on whether it is mixed with acid or bases . Example = onion

What are Olfactory Indicators?
Olfactory indicators are substances that change color or produce a distinctive odor when exposed to specific chemicals. They are commonly used in chemistry experiments to visually indicate the presence of certain substances. Olfactory indicators provide a simple and quick way to detect the presence of chemicals in a solution without the need for complex equipment.

Types of Olfactory Indicators
- Acids and Bases: Olfactory indicators can be used to detect the presence of acids or bases in a solution. For example, phenolphthalein changes color in the presence of a base, turning pink or red, while litmus paper changes color in the presence of an acid, turning red.
- Metal Ions: Olfactory indicators can also be used to detect the presence of specific metal ions in a solution. For example, potassium ferrocyanide reacts with iron ions to produce a blue color, indicating the presence of iron.
- Redox Reactions: Olfactory indicators can be used to detect the occurrence of redox reactions. For example, potassium permanganate changes color from purple to colorless in the presence of reducing agents.
- Complexation Reactions: Olfactory indicators can be used to detect the formation of complex ions in a solution. For example, EDTA forms a stable complex with metal ions, producing a color change.

Benefits of Olfactory Indicators
- Olfactory indicators provide a quick and easy way to visually detect the presence of specific substances in a solution.
- Olfactory indicators are often more cost-effective than electronic equipment for detecting chemical reactions.
- Olfactory indicators can be used in educational settings to help students understand chemical reactions and concepts.
In conclusion, olfactory indicators play a crucial role in chemistry experiments by providing a visual indication of chemical reactions and the presence of specific substances. They are valuable tools for both students and researchers in the field of chemistry.