How do acid/base indicators work?
Ok, since no one else is answering this question, I will take a stab at it. Ph indicators are organic dyes that absorb light in the visible range. Believe it or not, most organic substances do not absorb light in the visible range, so they are said to be “colorless”, usually clear or white. In order to get an organic substance to absorb in the visible range, it must have electrons that can vibrate freely over relatively long distances within the molecule. This is usually achieved using a series of double bonds all lined up in series, so that electrons are free to wander about through the entire length of the structure, jumping from one pi orbital to another, or more precisely, populating one giant pi orbital that stretches from one end of the molecule to the other. Aromatic arangements (benzene rings) are particularly helpful in this, but not absolutely necessary.
Ok, since no one else is answering this question, I will take a stab at it. Ph indicators are organic dyes that absorb light in the visible range. Believe it or not, most organic substances do not absorb light in the visible range, so they are said to be “colorless”, usually clear or white. In order to get an organic substance to absorb in the visible range, it must have electrons that can vibrate freely over relatively long distances within the molecule. This is usually achieved using a series of double bonds all lined up in series, so that electrons are free to wander about through the entire length of the structure, jumping from one pi orbital to another, or more precisely, populating one giant pi orbital that stretches from one end of the molecule to the other. Aromatic arangements (benzene rings) are particularly helpful in this, but not absolutely necessary. Nitrogen atoms introduced into the structure produce particularly favorable arrangements, hence the great aniline dye indus
