PH indicator solution is useful to make pH indicator paper. When pH indicators are used in a liquid form, the examine solution should be clear and colorless, whenever possible. At the time of testing, the sample has slight intrinsic color, test tools including a sliding comparator. The pH indicator paper works in the same way as the indicator solution itself: the paper changes color when it comes in contact with an acidic or basic substance. It can be utilized to balance for this intrinsic color. Various cases, colored solutionsor strongly turbid can be transformed into a clear and colorless for calculation by treatment or filtration with activated charcoal. The most regular procedure to obtain an idea about the pH solution is to utilize an acid base indicator. A pH indicators are a huge organic molecule that work like a " color dye". On the other side, various dyes do not transform color with the quantity of base or acid present, there are dozens of molecules called acid - base indicators, which do react to a alteration into the hydrogen ion concentration. A large number of indicators are themselves weak acids. A pH indicator is a halochromic chemical compound that is added in small amounts to a solution so that the pH of the solution can be determined visually. pH indicator solutions are often engaged in titration in analytical chemistry and biology to determine the extent of a chemical activity.