An indicator is a substance that changes its colour in acidic and basic medium. An indicator shows one colour in an acidic medium and different colours in a basic medium so that they are called indicators.
An olfactory indicator is a substance whose smell varies depending on whether it is mixed with an acidic or basic solution. These type of indicators are used in laboratories to check whether a given solution is a basic or an acidic solution by a process known as olfactory titration.
- There are certain substances whose odour (smell)changes in acidic or basic solutions. These substances are called olfactory indicators.
- The olfactory indicators have a characteristics odour.
- This odour in olfactory indicators is changed in acidic or basic solution and helps us in detecting whether a given sample solutions is acidic or basic in nature.
Onion, clove oil and vanilla extract are some of the examples.