Methyl orange is a pH indicator frequently used in titration because of its clear and distinct color variance at different pH values. Methyl orange shows red color in acidic medium and yellow color in basic medium. Because it changes color at the pKa of a mid strength acid, it is usually used in titration for acids.

Application

Methyl orange has the property to color alkaline and neutral water yellow. If the water becomes acidic, it turns red immediately. The point of change is at pH 4.3.