Chemical from common salt - class-XI

Slaked lime reacts with chlorine to give bleaching powder.

Bleaching powder is known as calcium hypochlorite. It is marketed as bleach powder. It is white solid although commercial samples appear yellow. It is not highly soluble in water and is used in soft to medium hard water. It has two forms dry and hydrated.

Baking soda is commonly known as sodium bicarbonate $ NaHC{ O } _{ 3 } $ used for cooking purposes.

Bleaching action takes place due to the hypochlorite radical [$ClO^{-}$].

The reaction of $NaCl$ and $CaCO _3$ gives sodium carbonate. But this reaction cannot be used for the manufacture of washing soda since it is a reversible reaction.

$2NaCl+CaCO _3\rightleftharpoons Na _2CO _3+CaCl _2$.

Hence the given statement is True.

Bleaching powder on reaction with cold water form milky solution of calcium hydroxide. 

$CaOCl _2+H _2O\rightarrow Ca(OH) _2+Cl _2$

Thus because of the lime present in it, it gives a milky solution when dissolved in water.

$CoCl _2$ is used as catalyst in the decomposition of bleaching powder.

When exposed to air, bleaching powder gives a smell of chlorine. This is because bleaching powder reacts with carbon dioxide from the atmosphere to produce calcium carbonate and chlorine.

In bleaching powder, $Ca(OCl)Cl$, the two $Cl$ atoms are in different oxidation states i.e., one $Cl^–$ having oxidation number of –1 and the other as $OCl^–$ having oxidation number of +1.

The reactions involved are-

Chlorine bleaches by the process of oxidation. It needs moisture for its bleaching action.

Chlorine reacts with water to form hydrochloric and hypochlorous acids.

$Cl _2 + H _2O \rightarrow HCl + HClO$

Hypochlorous acid is unstable, and it easily dissociates to form nascent oxygen.

$HClO \rightarrow HCl + [O]$

Nascent oxygen is a more powerful oxidising agent. Its formation is responsible for the bleaching nature of chlorine in the presence of moisture.

Bleaching powder (calcium oxychloride) is produced by the action of chlorine gas on dry slaked lime, which is Ca(OH)2.

The active constituent of bleaching powder is: $Ca(OCl) _2$

$Ca(OH) _2+\underset{\text{dry}}{Cl _2}\xrightarrow{below,35^oC} \underset{\text{Bleaching powder}}{CaOCl _2 + H _2O}$

The available chlorine is defined as the percentage of chlorine made available by bleaching powder when treated with dilute acids. The available chlorine present in bleaching powder sample is determined iodometricaliy by treating its solution with an excess of potassium iodide solution in the acidic medium.

Bleaching powder + ethanol $\rightarrow$ chloroform
Bleaching powder is used for bleaching cotton, wood pulp, it is also used as a disinfectant and germicide.

The bleaching powder has a strong bleaching action due to the formation of nascent oxygen.

Bleaching powder is calcium oxychloride which is formed by reacting calcium hydroxide with chlorine.

Chlorine is strongest bleaching property.

Calcium oxychloride (CaOCl₂) is known as bleaching powder. In the presence of small amount of dilute acid, it gives nascent oxygen which acts as an oxidising and bleaching agent. When it is treated with excess of dilute acids, chlorine is evolved which is responsible for the bleaching action of bleaching power.

The correct formula for Bleaching powder is CaOCl₂. One chlorine is directly bonded to calcium while other to the oxygen atom.

Bleaching powder is used as bleaching linen, wood pulp and washed clothes in laundry.

Calcium hypochlorite is an inorganic compound with formula $Ca(ClO) _2$. Calcium hydroxide and chlorine form bleaching powder. 

Formula of $calcium : hypochlorite$ is $\displaystyle Ca(ClO) _2$
$\displaystyle CaOCl _2$ represents $\displaystyle calcium : chlorohypochlorite$. It is known as $\displaystyle bleaching : powder$.

Reaction of bleaching powder with $dil.HCl$:

On long standing, bleaching powder undergoes auto-oxidation into calcium chlorate $Ca(ClO _3) _2$ and $ CaCl _2$.
 $6CaOCl _2 \rightarrow 6 Ca(ClO _3) _2  + 5 CaCl _2$.
The bleaching powder is $CaOCl _2$

Following are the uses of bleaching powder.
(A) It is used as a disinfectant in sterilization of water
(C) It is used as an oxidising agent in many chemical reactions in industry
(D) It is used for making wool unshrinkable
Bleaching powder is useful in preparation of organic solvent chloroform which is also used as an anesthetic.
Bleaching action is possible on cotton in textile industry, wood pulp in paper factories and washed clothes in laundary.

Bleaching powder loses oxygen in the presence of  cobalt chloride catalyst.
$2CaOCl _2 \xrightarrow {CoCl _2} 2CaCl _2 + O _2$

Bleaching powder is a yellowish white powder which gives a strong smell of chlorine.

Bleaching powder, $CaOCl _2$ or calciumoxychloride is used to kill germs and bacteria of water because it contains chlorine element, which is good disinfecting agent.

Bleaching powder is used for bleaching dirty clothes in the laundry, 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.It is also used for bleaching paper pulp,sterilizing water,making chloroform.

Heavy metals like Ni, Co, Mn, Cu and their chlorides accelerate the decomposition of bleaching powder.

$6Ca(OCl) _2 \rightarrow 6Ca(ClO _3) _2 + 5CaCl _2$

${ CaOCl } _{ 2 }+{ C } _{ 2 }{ H } _{ 5 }OH\rightarrow { CHCl } _{ 3 }+Ca{ \left( OH \right)  } _{ 2 }$

$2Cl _2 + 2Ca(OH) _2(conc.) \rightarrow Ca(OCl) _2 + CaCl _2 + 2H _2O$

Available chlorine in bleaching powder is the amount of chlorine liberated by the action of dilute acids on bleaching powder.

On long standing, bleaching powder undergoes auto-oxidation which results in the formation of calcium chloride and calcium chlorate.

$CaOCl _2+H _2O\rightarrow Ca(OH) _2+\underset {(\text {Pungent smelling gas})}{Cl _2}\uparrow$
$H _2S+Cl _2\rightarrow 2HCl+\underset {(\text {White turbidity})}{S}$
$\underset {(\text {Light green})}{2FeSO _4}+H _2SO _4+Cl _2\rightarrow Fe _2(SO _4) _3+2HCl$