Soap
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Soap is a salt of a fatty acid used in a variety of cleansing and lubricating products. In a domestic setting, soaps are surfactants usually used for washing, bathing, and other types of housekeeping. In industrial settings, soaps are used as thickeners, components of some lubricants, and precursors to catalysts.
A handmade soap bar
Box for Amigo del Obrero (Worker's Friend) soap from the 20th century, part of the Museo del Objeto del Objeto collection
Marseille soap in blocks of 600 g
Advertising for Dobbins' medicated toilet soap
Base (chemistry)
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In chemistry, there are three definitions in common use of the word "base": Arrhenius bases, Brønsted bases, and Lewis bases. All definitions agree that bases are substances that react with acids, as originally proposed by G.-F. Rouelle in the mid-18th century.
Ammonia fumes from aqueous ammonium hydroxide (in test tube) reacting with hydrochloric acid (in beaker) to produce ammonium chloride (white smoke).
Sodium hydroxide