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Thymol blue (thymolsulfonephthalein) is a brownish-green or reddish-brown crystalline powder that is used as a pH indicator. It is insoluble in water but soluble in alcohol and dilute alkali solutions.
Its transition range is around pH 9.3–10.5. Below this pH, it is colorless; above, it is blue. The molar extinction coefficient for the blue thymolphthalein dianion is 38,000 M −1 cm −1 at 595 nm. [2]
Thymol (also known as 2-isopropyl-5-methylphenol, IPMP), C 10 H 14 O, is a natural monoterpenoid phenol derivative of p-Cymene, isomeric with carvacrol.It occurs naturally in the oil of thyme, and it is extracted from Thymus vulgaris (common thyme), ajwain, [4] and various other plants as a white crystalline substance of a pleasant aromatic odor and strong antiseptic properties.
Solution: The main components of a universal indicator, in the form of a solution, are thymol blue, methyl red, bromothymol blue, and phenolphthalein. This mixture is important because each component loses or gains protons depending upon the acidity or alkalinity of the solution being tested. It is beneficial to use this type of universal ...
The general carbon skeleton of bromothymol blue is common to many indicators including chlorophenol red, thymol blue, and bromocresol green. [ 2 ] The presence of one moderate electron-withdrawing group ( bromine atom) and two moderate donating groups (alkyl substituents) are responsible for bromothymol blue's active indication range from a pH ...
Phenolphthalein's common use is as an indicator in acid-base titrations. It also serves as a component of universal indicator, together with methyl red, bromothymol blue, and thymol blue. [3] Phenolphthalein adopts different forms in aqueous solution depending on the pH of the solution.
Solution A: 0.02 g of thymol blue, 0.01 g cresol red and 2 mL of ethanol; Solution B: 0.8 g of sodium bicarbonate, 7.48 g of potassium chloride and 90 mL of water; Mix Solution A and B and mix 9 mL of the mixed solution to 1000 mL of distilled water.
The main use of litmus is to test whether a solution is acidic or basic, as blue litmus paper turns red under acidic conditions, and red litmus paper turns blue under basic or alkaline conditions, with the color change occurring over the pH range 4.5–8.3 at 25 °C (77 °F). Neutral litmus paper is purple. [2]