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Phenolphthalein's pH sensitivity is exploited in other applications: concrete has naturally high pH due to the calcium hydroxide formed when Portland cement reacts with water. As the concrete reacts with carbon dioxide in the atmosphere, pH decreases to 8.5–9. When a 1% phenolphthalein solution is applied to normal concrete, it turns bright pink.
Phthalide is an organic chemical compound with the molecular formula C 8 H 6 O 2. It is a white solid and the simplest benzo lactone . It is prepared from hydroxymethylbenzoic acid.
1,10-Phenanthroline (phen) is a heterocyclic organic compound. It is a white solid that is soluble in organic solvents. It is a white solid that is soluble in organic solvents. The 1,10 refer to the location of the nitrogen atoms that replace CH's in the hydrocarbon called phenanthrene .
A universal indicator is a pH indicator made of a solution of several compounds that exhibit various smooth colour changes over a wide range pH values to indicate the acidity or alkalinity of solutions. A universal indicator can be in paper form or present in a form of a solution. [1]
Its solution is colourless below pH 8.2, and purple above 9.8. Its molecular formula is C 22 H 18 O 4 . It is used medically to determine calcium levels in the human body, or to synthesize polyamides or polyimides.
PubChem CID. 31316; UNII: YG5I28WSQP ... Chemical formula. C 28 H 30 O 4: Molar mass: 430.544 g ... The molar extinction coefficient for the blue thymolphthalein ...
This is typically achieved by boiling an alkaline solution of phenolphthalein with powdered zinc, which reduces the phenolphthalein into phenolphthalin. Upon reduction, the very intense pink color of the cationic form of phenolphthalein fades to a faint yellow color. It is this form of phenolphthalein that is present in Kastle–Meyer test kits.
Its aqueous solution, if clear, is guaranteed to be free of carbonate, unlike those of sodium hydroxide and potassium hydroxide, as barium carbonate is insoluble in water. This allows the use of indicators such as phenolphthalein or thymolphthalein (with alkaline colour changes) without the risk of titration errors due to the presence of ...