Common Salt Chemicals-Sodium Hydroxide and Bleaching Powder

Introduction:

By now, we know that the combination of acid and base forms salt. Salts are formed as an effect of the neutralization of acids and bases; therefore, we can say that neutralization reactions form salts. For example, common salt (NaCl) can be formed by combining hydrochloric acid and sodium hydroxide solution. This common salt is very important for our body to maintain a balance of fluids and keep nerves and muscles running smoothly. In addition, NaCl is also widely used as a food preservative and taste enhancer in the food industry. Thus, The salt obtained is an important raw material for the substances we use daily, such as washing soda, baking soda, bleaching powder, and many more.

Let us learn more about how one substance, i.e., common salt (sodium chloride), is used to make all these different substances.

COMMON SALT

Common salt is a substance formed by combining hydrochloric acid and sodium hydroxide solution called sodium chloride.

HCl + NaOH → NaCl + water

Generally, the product of neutralization reactions is salt and water.

Sodium Hydroxide(NaOH)

Sodium hydroxide (NaOH) is a solid ionic compound.

Sodium hydroxide is called caustic soda and can be formed from sodium chloride.

Preparation of Sodium Hydroxide

1. Electrolysis of Brine:

Brine is the aqueous solution of sodium chloride. This brine solution on electrolysis produces sodium hydroxide as the principal product.

Electrolysis is a process in which the electric current is passed through an aqueous solution of ionic compounds to decompose into its constituent elements.

Commercially, NaOH is manufactured by the electrolysis of brine (NaCl solution).

1. When an electric current is passed through an aqueous solution of sodium chloride, it decomposes to form sodium hydroxide and chlorine.
2. This process is called chlor-alkali because the products obtained are (chlor for) chlorine and alkali. (Alkali as sodium hydroxide).

Process of Electrolysis:

On passing electricity through the brine solution, sodium chloride dissociates as Na⁺ and Cl^– ions:

The three products formed in this reaction include sodium hydroxide, chlorine, and Hydrogen. All are very useful.

2. By Heating Sodium Carbonate (Caustication Of Na₂CO₃)

Sodium hydroxide can also be prepared by heating 10 % Na₂CO₃ solution with milk of lime.

This process is also called as lime – caustic soda process.

Physical Properties of Sodium Hydroxide

a. Sodium hydroxide is a white crystalline translucent solid, deliquescent substance.

b. It is highly soluble in water and gives silky touch like soap

c. It is a highly corrosive solid.

Chemical Properties of Sodium Hydroxide

1. Reaction with Acid and Acidic Oxides:

Sodium hydroxide reacts with acid and acidic oxides to form salts.

With Acid:

When it reacts with acids like hydrochloric acids, the neutralization reaction takes place, and sodium chloride is obtained due to neutralization.