Bleaching Powder and Sodium Hydroxide

Introduction

In early times sunlight was used for the bleaching of substances. Charles Tennant in the year 1799 introduced a solid combination of chlorine and slaked lime. This is the major contributor to the production of a bleaching powder in bulk. Now it is available in many commercial products, and it is used for the bleaching of water that is to remove germs present in water. And in some chemical industries, it is used as an oxidizing agent. Sodium Hydroxide or caustic soda is also an important inorganic chemical compound that is found in many commercial products such as soap, detergents etc. And, in the extraction process of aluminium from its ore Bauxite.

What is the formula for Bleaching Powder?

The chemical name of the inorganic compound in the bleaching powder is calcium hypochlorite. It is a chemical used for the bleaching action which involves the decolouration of materials. And is a compound that has a smell of chlorine and an appearance of pale yellowish. Prepared by the reaction of chlorine gas on calcium hydroxide. So, the chemical formula of bleaching powder contains Calcium Oxygen and Chlorine elements. The chemical formula is $\mathrm{CaO(Cl)_{2}}$.

Preparation of Bleaching Powder

The reaction does the preparation of a bleaching powder with the help of freshly prepared chlorine gas and Calcium hydroxide or slaked lime. The chlorine gas used in this process is obtained from the electrolysis of brine solution. The reaction which involves the formation of bleaching powder is,

$$\mathrm{Ca(OH)_{2}\:+\:Cl_{2}\:\rightarrow\:CaO(Cl)_{2}\:+\:H_{2}O}$$

What is the use of Bleaching Powder?

There exist many uses for this inorganic compound. Some of its important uses are as pointed below.

• It is used for killing germs in the water.

• It is used in the textile industry for the bleaching of cotton and linen materials.

• They can be used for the manufacture of the chemical chloroform.

• It is used for the unshrinking of woollen materials.

• Is used for bleaching paper.

What is the formula for Sodium Hydroxide?

Caustic soda or Sodium hydroxide is also an important inorganic chemical compound that has many industrial and commercial applications. It is a white-coloured ionic compound that contains Sodium and Hydroxide ions. The presence of these two ions makes the chemical formula for sodium hydroxide as 𝑁𝑎𝑂𝐻. It is a highly corrosive alkaline compound. And it has a high tendency to absorb water. A series of hydrates with different chemical formulas is also present for this compound. It can be generally represented as $\mathrm{NaOH.nH_{2}O}$.

Preparation of Sodium Hydroxide

Electrolysis of sodium chloride in the Castner-Kellner cell is the main preparation of Sodium hydroxide. In this method carbon rod is used as the anode and mercury is used as the cathode. And the electrolyte used for the electrolysis of this method is Brine solution. The reactions that are taking place at the cathode and anode electrode result in the formation of sodium hydroxide.

At the cathode, the sodium ions produce a reduced sodium metal which then combines with the mercury to form a sodium amalgam. The reaction is,

$$\mathrm{Na^{+}\:+\:e^{-}\:+\:Hg\:\rightarrow\:Na\:-\:amalgam}$$

At the anode, the chlorine gas is produced by the oxidation of chloride ions. The reaction is,

$$\mathrm{Cl^{-}\rightarrow\:1/2Cl_{2}\:e^{-}}$$

The sodium amalgam obtained in the cathode is then further treated with water to produce sodium hydroxide. Hydrogen gas is also obtained as a by-product. The reaction is,

$$\mathrm{2Na\:-\:Hg\:+\:+\:2H_{2}O\:\rightarrow\:2NaOH\:+\:2Hg\:+\:H_{2}}$$

There is another method for the preparation of a sodium hydroxide in which the sodium metal is dissolved in water. But this reaction is a very explosive reaction in which flame and hydrogen gases are also produced. The reaction is,

$$\mathrm{2Na\:+\:2H_{2}O\:\rightarrow\:2NaOH\:+\:H_{2}}$$

This reaction is generally used for the demonstration of the reactivity of alkali metals.

What is the use of Sodium Hydroxide?

There are many applications of sodium hydroxide because of its chemical properties and inexpensive nature. Some of the important uses of sodium hydroxide are pointed out below.

• It is an important base in many chemical reactions.

• It is used in detergent manufacturing units.

• It is used to produce sodium salt.

• It has an important application in the petrol industry for increasing its alkalinity.

• It is used in salt spray testing for pH regulation.

Can you mix sodium hydroxide and bleach?

Bleach or bleaching powder that is used for household purposes generally contains a small amount of sodium hydroxide. Super cleaner will be obtained by the addition of further amounts of sodium hydroxide over bleach. The addition of sodium hydroxide must be careful; it does not exceed more than 5%. If an excess amount of sodium hydroxide is added to bleach it will spoil the whole bleach and make it a basic substance. And it may result in burning too.

Conclusion

Bleaching powder or calcium hypochlorite and Sodium hydroxide are important inorganic chemical compounds that have found application in many fields. They contain different elements such as sodium and calcium as metal is present. They are prepared in different methods too. Bleaching powder is obtained by the reaction of chlorine gas and caustic soda while Sodium hydroxide is obtained by the electrolysis of sodium chloride in the Castner-Kellner cell. Bleaching powder is used as a bleach and also acid is infected before killing germs present in the water. Sodium hydroxide is used in the manufacture of detergents, soaps, and the extraction of Aluminium metals.

FAQs

1. Is bleach poisonous to humans?

It is not a dangerous chemical compound but exposure to bleach has witnessed many problems in humans. It can cause problems to the lungs, eye irritation, skin irritation, etc. And also, it contains chlorine gas which then enters the blood and causes chlorine toxicity.

2. What is the reaction of a bleaching powder with water?

The reaction of a bleaching powder with water results in the formation of chlorine gases and Calcium hydroxide. The reaction is,

$$\mathrm{Ca(OCl)_{2}\:+\:H_{2}O\:\rightarrow\:Ca(OH)_{2}\:+\:CL_{2}}$$

3. Is sodium hydroxide safe?

Sodium hydroxide is not a safe chemical. The intake of Sodium hydroxide is very dangerous. As it results in vomiting, diarrhoea, nausea, stomach pain, etc. Exposure to sodium hydroxide to the skin often burns the skin.

4. Is sodium hydroxide a bleach?

The chemical compound obtained by the dissolution of sodium hydroxide and chlorine gas; Sodium hypochlorite is a bleach that is often used for household purposes.

5. What does sodium hydroxide do in skincare?

The alkaline nature of sodium hydroxide helps to maintain or regulate the pH of the skin. Since it is a basic substance. And in soap products, it is used for the process of saponification of oils.