What is the biological use of sodium hydroxide?

Answer 1

The most common use will be as a cleaning agent. NaoH is a strong base and it reacts with a fatty acid to form soap.

NaOH is also used in Aluminium production. It is added into the mineral bauxite (a mixture of hydrated Aluminium Oxide (Al2O3) and hydrated Iron Oxide (Fe2O3) and it will be reacting with Aluminium Oxide only to form Sodium Aluminate [NaAl(OH)4], which will be in a solution. After filtration takes place, Iron Oxide and other impurities will be separated with Sodium Aluminate.

Al2O3 + 3H2O + 2NaOH --> 2[NaAl(OH)4]

After that, Aluminium Oxide will precipitate due to the introduction of the Aluminium Hydroxide and then the precipitates are washed and heated to form pure Aluminium.

NaOH is also used in Cryolite (Na3AlF6). NaOH is reacted with Aluminium Oxide to produce another form of Sodium Aluminate (NaAlO2). NaAlO2 is then reacted with Hydrogen Fluoride (HF) to form Cryolite.

Al2O3 + 2NaOH = 2NaAlO2 + H2O

6HF + 3NaAlO2 = Na3AlF6 + 2Al(OH)3

Cryolite is a useful material that is used in the production of Potassium Aluminium Sulphate, Sodium Carbonate and Aluminium Sulphate. It also acts as a catalyst in the electrolysis of Aluminium extraction to lower Aluminium's melting point.