Potassium hydroxide potash lye

A base is any material that produces hydroxide ions when it is dissolved in water. The words alkaline, basic, and caustic are often used synonymously. Common bases include sodium hydroxide (lye), potassium hydroxide (potash lye), and calcium hydroxide (slaked lime). The concepts of strong versus weak bases, and concentrated versus dilute bases are exactly analogous to those for acids. Strong bases such as sodium hydroxide dissociate completely while weak bases such as the amines dissociate only partially. As with acids, bases can be either inorganic or organic. Typical reactions of bases include neutralization of acids, reaction with metals, and reaction with salts ... 

Sodium hydroxide (NaOFI), also called lye, soda lye, or caustic soda to distinguish it from potassium hydroxide (potash lye), is another important base. Flistorically, lye was obtained from the ashes of wood and used to make soap. Lye, however, is an extremely caustic chemical. It can cause serious chemical burns if it comes into contact with the skin and permanent blindness if it gets into the eyes. People had to be very careful while making the soap. They also had to make sure they got the mixture of lye and animal fat (lard) correct to keep from hurting themselves and their families. Because of its caustic (corrosive) nature, sodium hydroxide is also used as the active ingredient in oven and drain cleaners. 

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