Question

Define olfactory indicators. Name two subtances which can be used as olfactory indicator.​

Answer 1

Answer:

We know that an Olfactory indicator is a substance whose smell varies depending on whether it is mixed with an acidic or basic solution. Olfactory indicators can be used in the laboratory to test whether a solution is a base or an acid, a process called olfactory titration.

Answer 2

Answer:

Those substances whose smell (or odour) changes in acidic or basic solutions are called olfactory indicators.

Onion and vanilla extracts are olfactory indicators.

When a basic solution like sodium hydroxide is added to a cloth strip treated with onions (or onion extract), then the smell of onion vanishes.

And when sodium hydroxide is added to vanilla extract, it destroys the characteristic smell of vanilla.