Indigo carmine
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| Indigo carmine | |
|---|---|
 |
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| Other names | 5,5'-indigodisulfonic acid sodium salt |
| Identifiers | |
| CAS number | [] |
| Properties | |
| Molecular formula | C16H8N2Na2O8S2 |
| Molar mass | 466.36 |
| Appearance | purple solid |
| Melting point |
>300 °C |
| Solubility in water | 10 g/L (25 °C) |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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Indigo Carmine, or 5,5'-indigodisulfonic acid sodium salt, is a pH indicator with the chemical formula C16H8N2Na2O8S2.
[edit] Uses
The primary use of Indigo carmine is as a pH indicator. It is blue at pH 11.4 and yellow at 13.0.
| Indigo Carmine (pH indicator) | ||
| below pH 11.4 | above pH 13.0 | |
| 11.4 | ↔ | 13.0 |
[edit] Health concerns
Indigo carmine is harmful to the respiratory tract if swallowed. It is also an irritant to the skin and eyes. Proper laboratory cautions (Lab coat, gloves, goggles) are advised.
