The Story Of Washing Soda

What is washing soda (Na2CO3.10H2O)?

Washing soda finds its application in numerous ways, be it from household uses to a vast range of industrial applications. It is an alkaline compound with a high alkaline character which has the capability to remove adamant stains from clothes during washing. Washing soda formula is written as Na2CO3.10H2O. The chemical name of washing soda is sodium carbonate. Chemically soda ash is a hydrated salt of sodium carbonate. 

Solvay Process- Preparation of Sodium Carbonate

Steps involved in the manufacture of sodium carbonate are explained below:

  • Purification of Brine
  • Formation of sodium hydrogen carbonate
  • Formation of sodium carbonate
  • Recovery of ammonia

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Step 1: Purification of Brine

Concentrated brine is obtained by the process of evaporation and impurities like calcium, magnesium, etc are removed by the precipitation process. The concentrated brine solution undergoes filtration and is mixed with ammonia in the ammonia tower and the ammonia tower gets cooled.

Step 2: Formation of sodium hydrogen carbonate

In a carbonate tower, carbon dioxide is passed through an ammoniated brine solution.

NH3(aq) + CO2(g) + NaCl(aq) +H2O → NaHCO3(s) + NH4Cl(aq)

Step 3: Formation of sodium carbonate

Sodium Bicarbonate (NaHCO3) formed is obtained from the tower and is heated at a temperature of 300°C. Hence, formations of sodium carbonate take place.

2NaHCO→ Na2CO3 + CO2 + H2O

Step 4: Recovery of ammonia

Ammonia can be recovered by treating the solution of NH4Cl with Ca (OH)2. This ammonia is again used in the Solvay process and CaCl2 is obtained as a by-product.

2NH4Cl + Ca(OH)→ 2NH3 + CaCl2 + H2O

Physical properties and chemical properties of sodium carbonate:

  • It is a crystalline solid which is white.
  • It exists as a monohydrated salt (Na2CO3.10H2O), anhydrous salt (Na2CO3), heptahydrous salt (Na2CO3.7H2O) and decahydrate salt (Na2CO3.10H2O).
  • Sodium carbonate is basic in nature.
  • It has a melting point of 851°C.
  • In the presence of heat, it loses its water to form an anhydrous salt (soda ash).
    Na2CO3.10H2O → Na2CO3.H2O → Na2CO3 (at 373 K)

Uses of Washing Soda:

  • Used as a cleansing agent in industries and household.
  • It finds its application in paper, textile, soap, and detergent industries.
  • It is used in the process of softening of water.
  • It is used in the manufacturing of glass.
  • It is one of the most important agents in laundries.

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Frequently asked questions

1. What is the chemical formula of washing soda?

Ans: Na2CO3.10H2O

2. Washing soda is also known as ______.

ans: Soda ash.

3. The process by which sodium carbonate is obtained is called _______.

Ans: Solvay process.

4. Mention the four steps involved in the preparation of sodium carbonate.

Ans: The four steps involved in the preparation of sodium carbonate are:

  • Purification of Brine
  • Formation of sodium hydrogen carbonate
  • Formation of sodium carbonate
  • Recovery of ammonia

5. List two uses of washing soda.

  • Removes stains. Washing soda is highly alkaline, and can act as a solvent to remove stains.
  • Unclogs drains. Washing soda and boiling water can be used to unclog drains.
  • Removes greasy build-up in pots and pans. …
  • Cleans outdoor furniture. …
  • Cleans the washing machine.

Uses of Baking Soda

(1) It is used as an antacid in medicine to remove acidity of the stomach.

(2) It is used in making baking powder. Baking powder is a mixture of baking soda and a mild edible tartaric acid

Lime soda process is_____costly.

(A).  Moderate

(B).  High

(C).  Very high

(D).  Less

(E). None of these

Answer:   Less

For the turbid water____can be used.

(A).  Soap titration process

(B).  Lime soda process

(C).  Ion exchange process

(D).  Zeolite process

(E). None of these

Answer:   Lime soda process

In lime soda process hardness of water is reduced to about______

(A).  10-15ppm

(B).  35-40ppm

(C).  30-35ppm

(D).  15-30ppm

(E). None of these

Answer:   15-30ppm

In lime soda process the total dissolved solids are_______

(A).  Remains same

(B).  Not reduced

(C).  Reduced

(D).  Slightly reduced

(E). None of these

Answer:   Reduced

The reaction is carried out at______temperature for avoiding the reduction of the residual hardness, incomplete precipitation, and slow reaction.

(A).  30-40oC

(B).  40-50oC

(C).  60-70oC

(D).  50-60oC

(E). None of these

Answer:   50-60oC

_______are removed from the water by lime-soda process.

(A).  Minerals

(B).  Mineral complexes

(C).  Mineral alkaline

(D).  Mineral acids

(E). None of these

Answer:   Mineral acids

The only function of the batch process is to remove the hardness of the water on ______

(A).  Large scale

(B).  Small scale

(C).  Industrial purposes

(D).  Irrigation purposes

(E). None of these

Answer:   Small scale

In ____ amount, the coagulate is added in the hot lime sode process if needed.

(A).  High

(B).  Very low

(C).  Very high

(D).  Low

(E). None of these

Answer:   Very low

The remaining final hardness of water is about______ after treating by the hot lime-soda process.

(A).  10-15ppm

(B).  20-25ppm

(C).  15-20ppm

(D).  25-30ppm

(E). None of these

Answer:   20-25ppm

____is reduced because of heating at high temperature in the hot lime-soda process.

(A).  Time for treating

(B).  Energy

(C).  Cost

(D).  Corrosion of boiler

(E). None of these

Answer:  Corrosion of boiler

There are not steps in the lime-soda process.

(A).  False

(B).  True

(C). Partially True

Answer:  False

Due to _____ bacteria in the water is reduced to a minimum in hot lime-soda process.

(A).  Slow reactions

(B).  Faster reactions

(C).  High temperature

(D).  Low temperature

(E). None of these

Answer:   High temperature

When the tank gets filled then it indicates that ____, in batch process.

(A).  To stir more

(B).  To add the lime

(C).  To add the catalyst

(D).  Softening is completed

(E). None of these

Answer:   Softening is completed

_____is the reagent used in the lime-soda process.

(A).  Not regenerated

(B).  Regenerated

(C).  Regenerated depending on the hardness

(D).  Regenerated some times

(E). None of these

Answer:   Not regenerated

The change in hardness of water needs____, in the lime-soda process.

(A).  Change in dose of lime

(B).  Change in dose of soda

(C).  Change in dose either lime or soda

(D).  Change in dose of lime and soda

(E). None of these

Answer:   Change in dose of lime and soda


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