Sodium hydroxide

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Sodium hydroxide pellets on a glass dish

Sodium hydroxide is also known as caustic soda. Caustic means "burning" and caustic soda takes its name from the way it can burn the skin. It has the chemical formula of NaOH.

It is a base, meaning it has a very high pH. It is the most common thing used to raise the pH of things; for example, to neutralize an acid.

It dissolves easily in water, and makes the water warm when this happens. This means that it is an alkali

Sodium hydroxide is used as a solution named Lye to make soap. Lye is also used to unclog drains. Its dissolving properties and its ability to easily break surface tension are fundamental for its uses. It works in two ways. First, it combines with grease to make soap. Second, it dissolves hair (which is soluble in any basic solution).

Making sodium hydroxide[change | edit source]

Sodium hydroxide can be made (along with chlorine and hydrogen) using the chloralkali process. A solution of sodium chloride is electrolyzed and sodium hydroxide is made around the cathode, where water is reduced to hydrogen gas and hydroxide ion. The hydrogen is released and the hydroxide bonds with the sodium to make sodium hydroxide.[1]

2Na+ (from salt) + 2H2O → 2NaOH + H2 at cathode
2 Cl- (from salt) → Cl2 at anode

References[change | edit source]