How Does an Acid Base Indicator Work?
Chemical Identities of Indicators Acid-base indicators are chemicals that change color when they react with acids and bases. They change color depending on the pH (level of acidity) of a solution. Most indicators are in fact weak acids themselves, so they are able to react with either acids or bases. Each reaction produces a product of a different color. That is why indicators are able to change the color of a solution. Reactions of Indicators with Acids and Bases Indicators are present in solutions in two forms, noted as HIn and In-. Both of these have a distinct color. There are two possible reactions, depending on whether acid or base is introduced into the solution containing the indicator. If acid is added to the solution, more HIn is made. This changes the color of the solution to match that of HIn. If base is added instead, more In- is made, changing the color of the solution to that of In-. When reacted, the indicator simply changes to its other form, changing the color as well
