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# Bleaching Powder and Sodium hydroxide

## What is the Chemical Name of Bleaching Powder?

The chemical name of bleaching powder is calcium hypochlorite

## Common Salt (Sodium Chloride)

• Common salt is formed by the reaction between hydrochloric acid and sodium hydroxide.
• Its chemical name is sodium chloride (
$$\begin{array}{l}NaCl\end{array}$$
).

Common Salt

It exists as an important raw material for the production of various chemical compounds such as caustic soda (sodium hydroxide), bleaching powder

$$\begin{array}{l}Ca(OCl_2)\end{array}$$
, etc.

Let us have a look at the production of these compounds from common salt:

## Bleaching Powder

• Bleaching powder is a pale yellowish powder existing with a strong smell of chlorine.
• It is soluble in water but due to the presence of impurities, we never observe a clear solution.
• Its chemical formula is
$$\begin{array}{l}Ca(OCl_2)\end{array}$$
with its chemical name Calcium hypochlorite.

Calcium hypochlorite

### 1. Preparation of Bleaching Powder

Bleaching powder is synthesized by the action of chlorine gas (produced from the chlor-alkali process) on dry slaked lime (

$$\begin{array}{l}Ca (OH)_2\end{array}$$
).

$$\begin{array}{l}Ca(OH)_2 ~+ ~Cl_2~ → ~Ca(OCl_2) ~+~ H_2O\end{array}$$

### 2. Uses of Bleaching Powder

• It is used for bleaching dirty clothes in the laundry and as a bleaching agent for cotton and linen in the textile industry.
• It is a strong oxidizing agent, hence used as an oxidizer in many industries.
• It is used as a disinfectant which is used for disinfecting water to make potable water.

## Sodium Hydroxide

• Sodium hydroxide is a whitish solid, available in flakes, pellets and granules.
• It is popularly known as caustic soda.
• It is soluble in a polar solvent such as water but insoluble in non-polar solvents such as ether.

Sodium hydroxide crystal 3D ball structure

### 1. Preparation of Sodium Hydroxide

• Sodium hydroxide is synthesized through the chloralkali process. In this process, electricity is passed through an aqueous solution of sodium chloride (commonly called brine), and the decomposition of brine takes place.
• Chlorine gas is deposited at the anode while hydrogen at the cathode. The final solution of sodium hydroxide is formed at the cathode.
• As NaOH (an alkali) and chlorine gas are present in the final product, this process is known as the chloralkali process.

$$\begin{array}{l}2NaCl~ (aq)~ + ~2H_2O ~(l)~ \rightarrow~ 2NaOH ~(aq)~ + ~Cl_2~(g)~ + ~H_2~(g)\end{array}$$

Sodium Hydroxide (NaOH)

### 2. Uses of Sodium Hydroxide

• It is used for the manufacturing of paper, soaps, and detergents.
• It is used for degreasing metals.
• It is used to remove sulphurous impurities from poor quality crude oil by a process called caustic washing.

## Frequently Asked Questions – FAQs

### What is the formula for bleaching powder?

Bleaching Powder’s chemical formula is CaOCl2 and is called Calcium Oxychloride. It is prepared on dry slaked lime with chlorine gas.

### Is bleaching powder acidic or basic?

Bleaching powder is basic in character. It gives calcium chloride, chlorine and water when bleaching powder reacts with hydrochloric acid.

### What is the pH value of bleaching powder?

Bleach usually contains 5% sodium hypochlorite, which gives the skin a pH of about 11 and makes it mildly irritating.

### What is the importance of sodium hydroxide?

Sodium hydroxide (Na OH) is a metallic caustic base, also known as lye or caustic soda. An alkaline, caustic soda is widely used in many industries, mostly in the manufacture of pulp and paper, textiles, drinking water and detergents as a strong chemical base.

### Can you mix sodium hydroxide and bleach?

No response. Household bleach often contains a small amount of sodium hydroxide to prevent the decomposition of sodium hypochlorite. Sodium hydroxide is frequently used in reactions to increase the pH of sodium hypochlorite.

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