What is Acid-Base Indicators, and what is the difference between acid-base indicators and olfactory indicators

Answer 1

acid base indicators are used to indicate whether a solution is acidic or basic. They have one color in acid, another in base.

They are actually weak organic acids where the undissociated acid is one color and the dissociated anion is another. The solution pH where the indicator shifts from acid to base is dependant upon the indicator itself (reason is based on quantum mechanics and too deep to explanin herein). Some shift at lower pH, some at higher pH.

Indicators use visual color change to show the acid or base.

Olefactory indicators are based upon the olefactory sense, not the visual sense. Olefactory sense is the sense of smell.