What is universal indicator?
Answers
Explanation:
A universal indicator is a blend of pH indicator solutions designed to identify pH of a solution over a wide range of values. There are several different formulas for universal indicators, but most are based on a patented formula developed in 1933 by Yamada. A common mixture includes thymol blue, methyl red, bromothymol blue, and phenolphthalein.
How Colors Are Used
Color change is used to identify pH values. The most common universal indicator colors are:
Red 0 ≥ pH ≥ 3
Yellow 3 ≥ pH ≥ 6
Green pH = 7
Blue 8 ≥ pH ≥ 11
Purple 11 ≥ pH ≥ 14
However, the colors are specific to the formulation. A commercial preparation comes with a color chart that explains the expected colors and pH ranges.
While a universal indicator solution may be used to test any sample, it works best on a clear solution because it's easier to see and interpret the color change.
Explanation:
A universal indicator is a pH indicator made of a solution of several compounds that exhibits several smooth colour changes over a wide range pH values to indicate the acidity or alkalinity of solutions. ... Experiments with Yamada's universal indicator are also described in the Journal of Chemical Education.