Why does phenolphthalein turn pink in a base?
Why does phenolphthalein turn pink in a base?
Ionized molecules attract other molecules with the opposite charge and repel those with the same charge. Phenolphthalein is a weak acid and is colorless in solution although its ion is pink. Adding hydroxide ions (OH-, as found in bases) will change the phenolphthalein into its ion and turn the solution pink.
Why does the phenolphthalein change color?
Phenolphthalein Test It is an organic compound that we use as an acid or base indicator. Furthermore, the compound is pinkish in basic solution and colourless in acidic solution. Moreover, this change in colour is a result of ionization; that alter the charge and shape of Phenolphthalein molecule.
What is phenolphthalein commonly used for?
Phenolphthalein is an organic compound used as a laboratory reagent and pH indicator. Phenolphthalein exerts laxative effects by stimulating the intestinal mucosa and constricting smooth muscles.
What Colour does phenolphthalein turn in neutral?
Colourless
Other indicators
| Indicator | Acidic | Neutral |
|---|---|---|
| Methyl orange | Red | Yellow |
| Phenolphthalein | Colourless | Colourless |
What is the chemical formula for phenolphthalein?
Phenolphthalein is a chemical compound with the formula C 20H 14O 4 and is often written as “HIn” or “phph” in shorthand notation. Phenolphthalein is often used as an indicator in acid–base titrations. For this application, it turns colorless in acidic solutions and red in basic solutions.
What is the purpose of phenolphthalein?
Phenolphthalein is a mild acid that can be used for medical and scientific purposes. When used in medicine, this compound is most commonly recognized as an ingredient in over-the-counter laxatives. In laboratory settings, it is typically used to test the acidity of other substances.
Why does phenolphthalein change color?
This color change is a result of ionization, which alters the shape and charge of phenolphthalein molecules. This causes it to block the blue light spectrum when exposed to alkaline substances, producing a pink to purple hue.
What color do bases turn phenolphthalein?
The doubly deprotonated (In 2-) phenolate form (the anion form of phenol) gives the familiar pink color. In strongly basic solutions, phenolphthalein is converted to its In (OH) 3− form, and its pink color undergoes a rather slow fading reaction and becomes completely colorless above 13.0 pH.