Question

pH indicators detect the presence of H+ and OH- . They do this by reacting with H+ and OH-. Knowing this, agree or disagree with this statement and fully explain your answer.

Answer 1

Ph indicator detect the presence of H plus and OH minus, they do it by reaction with H plus And OH minus

PH indicator are weak acid or weak base.

weak acid pH indicator have conjugated base, so that weak acid can react with base and the basic form indicator can react with acid, and in certain pH range one form is dominating and impart color to the solution

For example phenolphthalein have two form HPh which is acidic form and Ph minus which is basic form in acidic medium it remain in Hph form since Hph is colorless so solution appears to be colorless but in basic medium it get ionized to ph minus which is pink in color, so solution appears to be pink