| Phenolphthalein (pH indicator) | | below pH 8.2 | | above pH 10.0 | | colorless | ⇌ | reddish purple | | Phenolphthalein is a sensitive chemical with the formula C20H14O4 (often written as "HIn" in shorthand notation). Often used in titrations, it turns colorless in acidic solutions and pink in basic solutions. If the concentration of indicator is particularly strong, it can appear purple. In solutions containing a pH below 0, phenolphthalein turns a bright orange color. A pH indicator is a halochromic chemical compound that is added in small amounts to a solution so that the pH (acidity or alkalinity) of the solution can be determined easily. ...
Image File history File links Phenolphthalein. ...
IUPAC nomenclature is a system of naming chemical compounds and of describing the science of chemistry in general. ...
A chemical formula (also called molecular formula) is a concise way of expressing information about the atoms that constitute a particular chemical compound. ...
The molecular mass (abbreviated MM) of a substance, formerly also called molecular weight and abbreviated as MW, is the mass of one molecule of that substance, relative to the unified atomic mass unit u (equal to 1/12 the mass of one atom of carbon-12). ...
In physics, density is defined as mass m per unit volume V. For the common case of a homogeneous substance, it is expressed as: where, in SI units: Ï (rho) is the density of the substance, measured in kg·m-3 m is the mass of the substance, measured in kg...
The melting point of a crystalline solid is the temperature at which it changes state from solid to liquid. ...
The boiling point of a substance is the temperature at which it can change its state from a liquid to a gas throughout the bulk of the liquid at a given pressure. ...
CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences, mixtures and alloys. ...
The simplified molecular input line entry specification or SMILES is a specification for unambiguously describing the structure of chemical molecules using short ASCII strings. ...
Titration setup: the titrant drops from the burette into the analyte solution in the flask. ...
Acidity redirects here. ...
Acids and bases: Acid-base reaction theories pH Self-ionization of water Buffer solutions Systematic naming Electrochemistry Acid-base extraction Acids: Strong acids Weak acids Mineral acids Organic acids Bases: Strong bases Weak bases Organic bases edit In chemistry, a base is most commonly thought of as a substance that...
In strongly basic solutions, phenolphthalein's pink color undergoes a rather slow fading reaction and becomes colorless again. In other words, the molecule has four forms:
| species | In | H2In | In2− | In(OH)3− | | structure | |
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 | | pH | < 0 | 0−8.2 | 8.2−10.0 | > 10.0 | | conditions | strongly acidic | acidic | alkaline | strongly alkaline | | color | orange | colorless | pink | reddish purple | | image | | |
 | | The rather slow fading reaction that produces the colorless In−OH3− ion is sometimes used in classes for the study of reaction kinetics. Image File history File links No higher resolution available. ...
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Phenolphthalein is insoluble in water, and is usually dissolved in alcohols for use in experiments. It is itself a weak acid, which can lose H+ ions in solution. The phenolphthalein molecule is colorless. However, the phenolphthalein ion is pink. When a base is added to the phenolphthalein, the molecule ⇌ ions equilibrium shifts to the right, leading to more ionization as H+ ions are removed. This is predicted by Le Chatelier's principle. Impact of a drop of water Water is a chemical substance that is essential to all known forms of life[1]. It covers 71% of Earths surface. ...
Functional group of an alcohol molecule. ...
In the scientific method, an experiment (Latin: ex-+-periri, of (or from) trying), is a set of actions and observations, performed in the context of solving a particular problem or question, to support or falsify a hypothesis or research concerning phenomena. ...
In chemistry, Le Chateliers principle can be used to predict the effect of a change in conditions on a chemical equilibrium. ...
Phenolphthalein is synthesized by condensation of phthalic anhydride with two equivalents of phenol under acidic conditions (hence the name). It was discovered in 1871 by Adolf von Baeyer. R-phrases , , , S-phrases , , , , , Flash point 152 °C RTECS number TI3150000 Supplementary data page Structure and properties n, εr, etc. ...
Phenol, also known under an older name of carbolic acid, is a colourless crystalline solid with a typical sweet tarry odor. ...
Johann Friedrich Wilhelm Adolf von Baeyer (October 31, 1835 - August 20, 1917) was a German chemist who synthesized indigo, and was the 1905 recipient of the Nobel Prize in Chemistry . ...
Uses
Phenolphthalein has been used for over a century as a laxative, but is now being removed from the market because of concerns over carcinogenicity. However, the small amounts usually used in experiments are harmless.[citation needed] Phenolphthalein is also commonly used in a mixture, primarily by forensic scientists, to test for the presence of blood. A laxative is a preparation used for encouraging defecation, or the expulsion of feces. ...
The term carcinogen refers to any substance, radionuclide or radiation which is an agent directly involved in the promotion of cancer or in the facilitation of its propagation. ...
Human blood smear: a - erythrocytes; b - neutrophil; c - eosinophil; d - lymphocyte. ...
Phenolphthalein is used to perform a presumptive blood test, and is commonly known as the Kastle-Meyer test. A dry sample is collected with a swab or filter paper. First a few drops of alcohol, then a few drops of phenolphthalein and finally a few drops of hydrogen peroxide are dripped onto the sample. If the sample turns pink then it is a positive test. This test is nondestructive to the sample; it can be kept and used in further tests at the lab. This test has the same reaction with blood from any animal, so further testing would be required to determine whether it originates from a human. A forensic presumptive blood test, where the chemical indicator Phenolphthalein is used. ...
Hydrogen peroxide (H2O2) is a very pale blue liquid which appears colourless in a dilute solution, slightly more viscous than water. ...
Phenolphthalein is used in toys, for example as a component of disappearing inks, or disappearing dye on the Hollywood Hair Barbie hair. In the ink it is mixed with sodium hydroxide, which reacts with carbon dioxide in the air. This reaction leads to the pH falling below the color change threshold as hydrogen ions are released via the reaction: Barbie is a best-selling doll launched at the American International Toy Fair on March 9, 1959. ...
Sodium hydroxide (NaOH), also known as lye or caustic soda, is a caustic metallic base. ...
- OH− (aq) + CO2 → CO32− (aq) + H+ (aq)
To develop the hair and "magic" graphical patterns, the ink is sprayed with a solution of hydroxide, which leads to the appearance of the hidden graphics by the same mechanism described above for colour change in alkaline solution. The pattern will eventually disappear by the same reaction with carbon dioxide detailed above. Thymolphthalein is used for the same purpose and in the same way, when blue color is desired. [1] Carbon dioxide is a chemical compound composed of one carbon and two oxygen atoms. ...
Thymolphthalein is an acid-base (pH) indicator. ...
 Phenolphthalein in alkaline solution Image File history File linksMetadata Size of this preview: 800 × 532 pixel Image in higher resolution (1000 × 665 pixel, file size: 358 KB, MIME type: image/jpeg) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Phenolphthalein User:Benjah...
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See also Bromothymol blue (alt: dibromothymolsulfonephthalein, bromthymol blue, BTB) is a chemical indicator for weak acids and bases. ...
A pH indicator is a halochromic chemical compound that is added in small amounts to a solution so that the pH (acidity or alkalinity) of the solution can be determined easily. ...
Universal Indicator is a pH indicator that has different colors to indicate the range of the pH of the solution it is in. ...
External links - Page on different titration indicators, including phenolphthalein
- Links to external chemical sources
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