Sodium Hydroxide

First identify NaOH as sodium hydroxide. Then remember that it dissolves to give hydroxide ions. Finally connect those ions with strong basic behaviour and common uses.

A beaker sketch with NaOH pellets dissolving in water and a red litmus strip changing to blue is enough for revision.

A common wrong answer is to call NaOH a salt because it contains sodium. That is wrong because its chemical behaviour is basic, not neutral.

Sodium hydroxide is a strong base, also called caustic soda, that dissolves in water to give a highly basic solution.

Sodium hydroxide is a strong base, also called caustic soda, that dissolves in water to give a highly basic solution. NaOH dissolves in water to give Na⁺ and OH^- ions. The OH^- ions are responsible for its strong basic nature. A dilute sodium hydroxide solution turns red litmus blue and has a very high pH.

Sodium hydroxide is one of the most important laboratory and industrial chemicals in this chapter. It is used in soap making, paper manufacture, and cleaning processes. Because it is strongly basic, it must be handled carefully. In water it produces hydroxide ions, which give its strong basic nature. NaOH dissolves in water to give Na⁺ and OH^- ions. The OH^- ions are responsible for its strong basic nature. If a student tests NaOH solution with red litmus, the litmus turns blue. That shows the solution is strongly basic and confirms sodium hydroxide as a base. Questions often ask for the nature, use, or litmus behaviour of sodium hydroxide, or ask why it must be handled carefully. A common wrong answer is to call NaOH a salt because it contains sodium. That is wrong because its chemical behaviour is basic, not neutral.