//Sodium Hydroxide

Sodium Hydroxide

Sodium Hydroxide

What is Sodium Hydroxide? 

Sodium hydroxide highly soluble in water, also readily absorbs moisture and carbon dioxide from the air. In addition, it forms a series of hydrates NaOH·nH
2O. The monohydrate NaOH·H
2O crystallizes from water solutions between 12.3 and 61.8 °C. It`s a highly caustic base and alkali that decomposes proteins at ordinary ambient temperatures and may cause severe chemical burns.


Sodium hydroxide was first prepared by soap makers. NaOH making was as part of soap making in an Arab book of the late 13th century.By passing water repeatedly through a mixture of alkali and quicklime (calcium oxide, CaO). NaOH solution was obtained of this process.

European soap makers also followed this recipe. In 1791 the French chemist and surgeon Nicolas Leblanc patented a process for mass-producing sodium carbonate. “Soda ash” was replaced by that.  However, by the 20th century, the electrolysis of sodium chloride had become primary method for producing sodium hydroxide

Sodium Hydroxide properties:

Physical properties:

Pure sodium hydroxide is a colorless crystalline solid that melts at 318 °C without decomposition. Furthermore highly soluble in water, with a lower solubility in polar solvents such as ethanol and methanol. NaOH also insoluble in ether and other non-polar solvents.

Dissolution of NaOH in water is highly exothermic reaction. Resulting solution also is usually colorless and odorless. As with other alkaline solutions, it feels slippery with skin contact due to the process of saponification that occurs between NaOH and natural skin oils.

Crystal structure:

Mono-hydrate crystallizes in the space group Pbca, with cell dimensions a = 1.1825, b = 0.6213, c = 0.6069 nm. Atoms are arranged in hydrargillite-like layer structure /O Na O O Na O/…
In addition, each sodium atom is pent by six oxygen atoms, three each from hydroxyl anions HO− and three from water molecules. Hydrogen atoms of the hydroxyls form strong bonds with oxygen atoms within each O layer.


Industrially Caustic soda produced as 50% solution by variations of electrolytic chloralkali process. Cl gas also produced in this process. In addition, solid NaOH obtained by evaporation of water.

Historically, it was produced by treating sodium carbonate with calcium hydroxide in a metathesis reaction. Sodium hydroxide is soluble while calcium carbonate is not.

Ca(OH)2(aq) + Na2CO3(s) → CaCO3 ↓ + 2 NaOH(aq)

It also produced by combining pure sodium metal with water. The by-products are hydrogen gas and heat, often resulting in a flame, making this a common demonstration of the reactivity of alkali metals in academic environments.


caustic soda has popular uses in industry. In bulk, it mostly handled as aqueous solution, since solutions are cheaper and easier to handle. Around 56% have industrial uses. It also used in sodium salts, detergents, pH regulation, and organic synthesis factories. Also used in the Bayer process of aluminium production.

NaOH used in scenarios where it`s desirable to increase the alkalinity of a mix. Furthermore it uses in neutralize acids.

For example, in petroleum, It used as an additive in drilling mud. It increase alkalinity in bentonite mud systems. So increase mud viscosity, to neutralize acid gas (H2S, CO2, …) who encountered in geological formation as drilling progresses.



Sodium Hydroxide
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Sodium Hydroxide
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