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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 by the reaction:
For example, sodium hydroxide, NaOH, is a strong base. NaOH(aq) → Na + (aq) + OH − (aq) Therefore, when a strong acid reacts with a strong base the neutralization reaction can be written as H + + OH − → H 2 O. For example, in the reaction between hydrochloric acid and sodium hydroxide the sodium and chloride ions, Na + and Cl − take ...
A liquid fat sample combined with neutralized 95% ethanol is titrated with standardized sodium hydroxide of 0.1 eq/L normality to a phenolphthalein endpoint. The volume and normality of the sodium hydroxide are used, along with the weight of the sample, to calculate the free fatty acid value. [3]
Sodium hydroxide, also known as lye and caustic soda, [1] [2] is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations Na + and hydroxide anions OH −. Sodium hydroxide is a highly corrosive base and alkali that decomposes lipids and proteins at ambient temperatures and may cause severe ...
Sodium hydroxide is used in the manufacture of soap, paper, and the synthetic fiber rayon. Calcium hydroxide (slaked lime) is used in the manufacture of bleaching powder. Calcium hydroxide is also used to clean the sulfur dioxide, which is caused by the exhaust, that is found in power plants and factories. [9]
A universal indicator is usually composed of water, 1-propanol, phenolphthalein, sodium hydroxide, methyl red, bromothymol blue, sodium bisulfite, and thymol blue. [5] The colours that indicate the pH of a solution, after adding a universal indicator, are:
A well-known application of this reactivity is the preparation of the anthraquinone dye quinizarin by reaction with para-chlorophenol followed by hydrolysis of the chloride. [7] Phenolphthalein can be synthesized by the condensation of phthalic anhydride with two equivalents of phenol under acidic conditions (hence
Ferroxyl indicator, or rust indicator, is a solution containing potassium hexacyanoferrate(III), phenolphthalein and sodium chloride. It turns blue in the presence of Fe 2+ ions, and pink in the presence of hydroxide (OH-) ions. It can be used to detect metal oxidation, and is often used to detect rusting in various situations.