Sodium chloride and Sodium hydroxide
Sodium chloride (NaCl), commonly known by the names table salt, rock salt, sea salt, or common salt, is a white, crystalline, hygroscopic solid with a melting point of 1081K and a boiling point of 1713K necessary chemical with a wide range of applications in both daily life and industry. Seawater contains about 2.95 percent NaCl, while brine is a concentrated 28 percent aqueous NaCl solution. Seawater is the primary source of sodium chloride, as it evaporates when exposed to sunshine. But the unprocessed salt contains impurities including calcium chloride (CaCl₂), magnesium chloride (MgCl₂), and calcium sulfate (CaSO₄).
This Story also Contains
- Sodium Chloride(NaCl)
- Preparation
- Physical Properties
- Uses
- Sodium Hydroxide(NaOH)
- Preparation
- Physical Properties
- Uses
- Some Solved Examples
- Conclusion
Sodium hydroxide (NaOH), or caustic soda, is another crucial chemical with a variety of industrial and laboratory uses. It is created by heating a solution of ferric oxide and sodium carbonate to create sodium ferrite, which is subsequently hydrolyzed to form NaOH. Other techniques include the Causticization or Gossage Method, which creates NaOH by mixing lime (CaO + Ca(OH)₂) with sodium carbonate. Sodium hydroxide (NaOH) is a white, crystalline, deliquescent solid that dissolves more readily in water than alcohol. It has a soapy texture and a melting point of 591 Kelvin.
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Sodium Chloride(NaCl)
It is called common salt, rock salt, sea salt, or table salt. Seawater has nearly 2.95% NaCl. 28% aqueous NaCl solution is called brine.
Preparation
It is mainly manufactured from seawater by evaporation in the sun. As it contains impurities of MgCl2, CaCl2, CaSO4 hence it is further purified by passing HCl gas where due to the common ion effect pure NaCl gets precipitated.
Physical Properties
- It is a white crystalline solid and hygroscopic in nature.
- It melts at 1081K and boils at 1713K.
- It dissolves in water and the process of dissolution is endothermic.
- Its solubility is 36g per 100g of water at 273K. The solubility does not increase much with the increase in temperature.
Uses
- It is an essential constituent of our food.
- It is used in the manufacture of sodium, sodium hydroxide, washing soda, hydrogen chloride, chlorine, etc.
- It is used in freezing the mixture.
- It is used for the preparation of soap.
- It is used for regenerating ion exchange resins.
Sodium Hydroxide(NaOH)
It is also known as caustic soda.
Preparation
It is prepared by the following methods:
- Gossage or Causticization Method
In this method, a suspension of lime [CaO+Ca(OH)2] is treated with sodium carbonate to obtain NaOH as follows:Na2CO3+Ca(OH)2→2NaOH+CaCO3 - Lowig's Method
Here a mixture of sodium carbonate and ferric oxide is heated in a revolving furnace up to redness to get sodium ferrite which is first of all cooled and hydrolyzed by hot water into NaOH solution and insoluble ferric oxide. The solution is filtered and evaporated up to dryness to get the flacks of NaOH.
Na2CO3+Fe2O3→ Fusion 2NaFeO22NaFeO2→H2O,Δ2NaOH+Fe2O3
Physical Properties
- It is a white crystalline, deliquescent soapy solid with a melting point of 591.4K.
- It is highly soluble in water but less soluble in alcohol.
- It is corrosive in nature and bitter in taste.
Uses
- The manufacture of soap, paper, artificial silk, and a number of chemicals.
- In petroleum refining.
- In the purification of bauxite.
- In the textile industries for mercerizing cotton fabrics.
- For the preparation of pure fats and oils,
- As a laboratory reagent.
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Some Solved Examples
Q.1 A white sodium salt dissolves readily in water to give a solution that is neutral to litmus. When silver nitrate solution is added to the aforementioned solution, a white precipitate is obtained which does not dissolve in dil. nitric acid. The anion is :
1).CO32-
2).SO42-
3).Cl-
4).S2-
Solution:
As we learned in
NaCl→Na++Cl−→AgNO3AgCl+NaNO3 (Neutral) (White ppt) AgCl does not dissolve in HNO3
Hence, the answer is option (3).
Q.2 NaOH can be prepared by :
Electrolysis of concentrated solution of KCl
Electrolysis of concentrated solution of Na2CO3
Electrolysis of concentrated solution of NaHCO3
Electrolysis of concentrated solution of NaCl
Solution:
As we learned
Preparation of NaOH by Electrolytic method -
By electrolysis of a concentrated solution of NaCl
NaCl(aq)→Na++Cl−
At anode: 2Cl−→Cl2+2e−
At cathode: 2H2O+2e−⇌H2+2OH−
Na++OH−→NaOH
NaOH can be prepared by electrolysis of a concentrated solution of NaCl
Hence, the answer is the option (4).
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Conclusion
Summary of Sodium Chloride (NaCl)
- Common salt, rock salt, sea salt, and table salt are some of the names for sodium chloride (NaCl).
- Occurrence: In seawater, 2.95 percent of the concentration is present. The preparation involves evaporating seawater using sunlight and then using HCl gas to remove any impurities.
- Physical features include being white, crystalline, and hygroscopic (able to absorb moisture). At 1713K, it boils, and at 1081K, it melts.
- Applications: Hydrogen chloride, washing soda, sodium hydroxide, and chlorine generation; the latter is necessary for food manufacturing. Its other applications include the manufacture of soap, freezing combinations, and ion exchange resin regeneration.
Summary of Sodium Hydroxide (NaOH)
- Caustic soda, commonly referred to as sodium hydroxide or NaOH
- White, crystalline, foamy solid, and deliquescent (absorbing moisture) are some of its physical features with melting point.591.41°C
- Applications include the manufacturing of paper, soap, synthetic silk, and other compounds. used to prepare clean fats and oils, refine petroleum, purify bauxite, and mercerize cotton for the textile industry.
Frequently Asked Questions (FAQs)
