Phenolphthalein is often abbreviated as “HIn” or “Ph” in shorthand. It belongs to the class of phthalein dyes and is a weak acid that can lose H+ ions in solution. Phenolphthalein is colorless in its non-ionized form and changes to fuchsia in its double-deprotonated state. It exhibits various colors depending on the pH of the medium. This compound is slightly soluble in water and usually dissolves in alcohol for experiments. Phenolphthalein was first synthesized by Adolf von Baeyer in 1871 via the condensation of phthalic anhydride with phenol. 
CAS No.: 77-09-8
Synonyms: Phthalimetten; Euchessina; Phthalin; Espotabs; Phenolax; Purgophen; Koprol; Laxogen
| Physical Properties | |
| Chemical formula | C20H14O4 |
| IUPAC Name | 3,3-bis(4-hydroxyphenyl)-2-benzofuran-1-one |
| Molecular weight | 318.3 g/mol |
| Solubility | Water, Alcohol, Ethanol, and Acetone |
| Flash point | > 9.7 °C at 1,013 hPa |
| Density | 1.3 g/cm³ |
| Chemical Properties | |
| Color | White to Off-white |
| State | Solid powder |
| Melting point | 262.5 °C |
| λmax | 553 nm |
| pKa | 9.3 |
| Pictograms : |   |
| Hazard Statements : | H315: Causes skin irritation. |
| Precautionary statements : | P202: Do not handle until all safety precautions have been read and understood. |
Phenolphthalein is often abbreviated as “HIn” or “Ph” in shorthand. It belongs to the class of phthalein dyes and is a weak acid that can lose H+ ions in solution. Phenolphthalein is colorless in its non-ionized form and changes to fuchsia in its double-deprotonated state. It exhibits various colors depending on the pH of the medium. This compound is slightly soluble in water and usually dissolves in alcohol for experiments. Phenolphthalein was first synthesized by Adolf von Baeyer in 1871 via the condensation of phthalic anhydride with phenol.
CAS No.: 77-09-8
Synonyms: Phthalimetten; Euchessina; Phthalin; Espotabs; Phenolax; Purgophen; Koprol; Laxogen
| Physical Properties | |
| Chemical formula | C20H14O4 |
| IUPAC Name | 3,3-bis(4-hydroxyphenyl)-2-benzofuran-1-one |
| Molecular weight | 318.3 g/mol |
| Solubility | Water, Alcohol, Ethanol, and Acetone |
| Flash point | > 9.7 °C at 1,013 hPa |
| Density | 1.3 g/cm³ |
| Chemical Properties | |
| Color | White to Off-white |
| State | Solid powder |
| Melting point | 262.5 °C |
| λmax | 553 nm |
| pKa | 9.3 |
| Pictograms : | |
| Hazard Statements : | H315: Causes skin irritation. |
| Precautionary statements : | P202: Do not handle until all safety precautions have been read and understood. |
Phenolphthalein turns pink in basic solutions with a pH above 8.3.
Phenolphthalein is colorless in acidic solutions.
Phenolphthalein solution turns pink in the presence of a base because the hydroxide ions react with the acidic group in the phenolphthalein, forming ions that transmit a pink color to the solution. This reaction allows phenolphthalein to act as an acid-base indicator in titrations.
Phenolphthalein is a chemical compound used as an acid-base indicator. It is colorless in acidic solutions and turns pink in basic solutions, making it useful in titrations to determine the pH of a solution.
The phenolphthalein test is a chemical test used to detect the presence of blood. In this test, phenolphthalein reacts with hemoglobin in blood, turning pink if blood is present.
