Methyl orange
From Biocrawler, the free encyclopedia.
Methyl Orange is a pH indicator frequently used in titrations. It is also toxic.
It is often chosen to be used in titrations because of its clear colour change. Unlike universal indicator, methyl orange doesn't have a full spectrum of colour change, but has a sharper end point.
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Indicator Colours
| Methyl orange (pH indicator) | ||
| below pH 3.1 | above pH 4.4 | |
| red | ↔ | yellow |
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Methyl Orange moves from red through orange and to yellow, or from yellow through orange to red. This colour change can be rather subtle, making methyl orange less than ideal for many titrations.
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Chemical Information
Methyl orange solid is usually sold as a sodium salt of the acid:
Sodium p-Dimethylaminoazobenzenesulfonate
C14H14N3O3SNa
4-NaOSO2C6H4N:NC6H4-4-N(CH3)2
Its formula weight is approximately 327.34 grams per mole.
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Other Indicators
- Phenolphthalein is another indicator frequently used in acid-base titration reactions because of its very sharp color change.
- A number of other common indicators are tabulated in the article on pH indicators.
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External links
- Informative page on different titration indicators, including Methyl Orange (http://www.chemguide.co.uk/physical/acidbaseeqia/indicators.html)
