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Universal Indicator

A universal indicator indicates the pH of a substance in a more complex way than most pH indicators. Instead of changing colors if the pH of a substance it is exposed to is above or below a certain pH point, a universal indicator changes to a color that is calibrated to indicate the pH level of the substance.

A universal indicator is typically composed of water, methanol, propan-1-ol, phenolphthallien sodium salt, methyl red sodium salt, phenol,4,4'-(3h-2,1-benzoxathiol-3-ylidene)bis2-bromo--methy l-6-(1-methylethyl)-, s,s-dioxide, monosodium salt, and phenol,4,4'-(3h-2,1-benzoxathiol-3-ylidene)bis5-methyl2-(1-m ethylethyl)-, s,s-dioxide, monosodium salt.

Due to properties in several of its ingredients, the universal indicator is a flammable liquid with some health hazards. It can irritate the respiratory tract if inhaled or burned, and repeated or prolonged contact can cause kidney damage or skin damage. In addition to its normal flammability, the universal indicator sometimes forms explosive peroxides.

1. Very acidic - Red
2. Acidic - Orange/Yellow
3. Neutral - Green
4. Basic/base/alkali - Blue
5. Very basic/base/alkali - Purple

Web Resources On Universal Indicator

Acids and Alkalis
Indicators

Book Resources On Universal Indicator

Understanding Acid-Base by Benjamin Abelow
Acid-Base, Fluids, and Electrolytes Made Ridiculously Simple by Richard Arthur Preston

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