Phenolphthalein is an indicator that turns from clear to pink in a basic solution, according to Reference.com. In a strongly acidic solution, the indicator is orange, but in the pH range of 0 to 8.2 it is clear. The indicator is pink in solutions with a pH of 8.2 to 12, but turns colorless again in strong bases above this pH range.Know More
Reference.com indicates that phenolphthalein is a weak acid itself that in molecular form is colorless. The addition of a base to a solution of phenolphthalein removes hydrogen ions from the solution, creating more phenolphthalein ions, which causes the color to change.
Chemists use titrations to determine the concentration of an unknown acid or base. They add the opposite reagent of known concentration and carefully measure the amount needed to cause the color change. About.com says, "For a properly performed titration, the volume difference between the end point and the equivalence point is small." At the equivalence point, V1N1 = V2N2, where V is volume and N is the concentration of the acid or base.
Reference.com says that universal indicators are a mix of phenolphthalein, and the indicators methyl red, bromothymol blue, and thymol blue. By mixing several indicators, chemists create a single solution that is useful in determining pH over a wide range.Learn more about Chem Lab
Colors on a universal indicator pH chart include: red, orange and yellow for acids, light green for neutral, and green, blue and violet for bases. The universal indicator chart assigns a color to each pH level on a scale of four to 10 pH.Full Answer >
Phenolphthalein, an acid-base indicator used to test the pH of a solution, turns pink due to the presence of a weak base. The indicator itself is a weak, colorless acid that forms pink anions when it dissolves in water.Full Answer >
Phenolphthalein, which is an acid-base pH indicator, is a weak acid. For this reason, this indicator is colorless in the presence of acids that are also associated with a high concentration of hydrogen ions. In the presence of a basic solution, phenolphthalein changes to a pink color because bases are associated with a concentration of hydroxide ions.Full Answer >
Phenolphthalein is a weak acid used in titration to provide visual indication of the equilibrium point between the concentration of moles of acid and moles of base. Phenolphthalein is colorless when in an acidic solution and pink when in a basic solution.Full Answer >