Question

What are olfactory indicators and litmus paper

Answer 1

Olfactory indicators are used to distinguish between acids and bases. Their smell varies in acidic and basic solution.

Examples:

1. Onion: It loses its characteristic smell in Basic solution and retains its smell in Acidic solution
2. Litmus is a water-soluble mixture of different dyes extracted from lichens. It is often absorbed onto filter paper to produce one of the oldest forms of pH indicator, used to test materials for acidity.Blue litmus paper turns red under acidic conditions and red litmus paper turns blue under basic or alkaline conditions, with the color change occurring over the pH range 4.5–8.3 at 25 °C (77 °F). Neutral litmus paper is purple.