Eriochrome Black T is a complexometric indicator and an azo dye. A deprotonated structure appears blue but changes to red when it forms a complex with metal ions like calcium and magnesium. In a buffered solution at pH 10, it is blue, and adding metal ions causes it to change color. This indicator is commonly used to signal the end-point of complexometric titrations.
CAS No.: 1787-61-7
Synonyms: Mordant Black 11; Solochrome Black T; Fast Chrome Black T; Solochrome Black; Potting Black C; Chrome Black T
| Physical Properties | |
| Chemical formula | C20H12N3O7SNa |
| IUPAC Name | 3,3-bis(4-hydroxyphenyl)-2-benzofuran-1-one |
| Molecular weight | 461.381 g/mol |
| Solubility | Soluble in Water and Ethanol |
| Flash Point | 185 °C |
| Density | 2.165 g/cm³ |
| Chemical Properties | |
| Colour | Dark Red/Brownish-black solid with a faint metallic sheen |
| State | Solid Powder |
| Melting point | 801 °C |
| pKa | 6.3 |
| Pictograms : |
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| Hazard Statements : | H225: Highly flammable liquid and vapour |
| Precautionary statements : | P210: Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking. |
Eriochrome Black T is a complexometric indicator and an azo dye. A deprotonated structure appears blue but changes to red when it forms a complex with metal ions like calcium and magnesium. In a buffered solution at pH 10, it is blue, and adding metal ions causes it to change color. This indicator is commonly used to signal the end-point of complexometric titrations.
CAS No.: 1787-61-7
Synonyms: Mordant Black 11; Solochrome Black T; Fast Chrome Black T; Solochrome Black; Potting Black C; Chrome Black T
| Physical Properties | |
| Chemical formula | C20H12N3O7SNa |
| IUPAC Name | 3,3-bis(4-hydroxyphenyl)-2-benzofuran-1-one |
| Molecular weight | 461.381 g/mol |
| Solubility | Soluble in Water and Ethanol |
| Flash Point | 185 °C |
| Density | 2.165 g/cm³ |
| Chemical Properties | |
| Colour | Dark Red/Brownish-black solid with a faint metallic sheen |
| State | Solid Powder |
| Melting point | 801 °C |
| pKa | 6.3 |
| Pictograms : |
|
| Hazard Statements : | H225: Highly flammable liquid and vapour |
| Precautionary statements : | P210: Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking. |
Eriochrome Black T is acidic due to the occurrence of sulfonic acid groups in its structure.
Yes, EDTA binds with Eriochrome Black T, displacing it from metal ions and causing a color change.
To prepare an Eriochrome Black T indicator, dissolve 0.5-1 g of Eriochrome Black T powder in distilled water to make a 0.1% to 0.5% solution. Filter if necessary and store in a light-proof, airtight container.
Yes, Eriochrome Black T helps determine water hardness by forming a complex with metal ions in water, which changes color during titration.
Eriochrome Black T is used primarily as an indicator in complexometric titrations, such as determining water hardness and detecting metal ions.
