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Universal indicator

Universal Indicator is a pH indicator that transitions through numbers 3-12 (on the pH chart) to indicate the acidity and alkaline of solutions. Although there are a number of commercially available universal pH indicators, most are a variation of a formula patented by Yamada in 1923.[1] Details of this patent can be found in Chemical Abstracts.[2]

Experiments with Yamada’s Universal Indicator are also described in the Journal of Chemical Education.[3]


Potential hazards

Yamada's Universal Indicator is a flammable liquid. The indicator dyes should be considered toxic by ingestion and skin contact should also be avoided[citation needed].

More details

  • Physical state: Liquid
  • Appearance: light green in water solvent; dark green alone
  • Odour: alcohol-like, occasionally likened to vanilla.
  • pH value: Approximately 7
  • Vapour pressure: 25 mmHg (3.3 kPa)
  • Vapour Density: 1.3 kg/m³
  • Boiling point: 80 °C
  • Solubility: Soluble in water.
  • Specific gravity/Density: 0.93 g/cm³
  • Molecular formula: Mixture

"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."[4]

See also


  1. ^ Jap. Pat. 99,664, Feb 21, 1933
  2. ^ Chem Abstr, 28, 2258 (1934)
  3. ^ For a discussion of these experiments, as well as recipes for Yamada and other universal indicators, see Foster, S.F. and Gruntfest, J.Chem.Educ., 14, 274(1937)
  4. ^ "Universal Indicator." ISCID Encyclopedia of Science and Philosophy.
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Universal_indicator". A list of authors is available in Wikipedia.
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