Question

how is washing soda prepared from sodium carbonate? Give its chemical equation. State the type of this salt .Name the type of hardness of water which can be removed by it?

Answer 1

Answer:

Firstly, a cold and concentrated sodium chloride solution is reacted with ammonia and carbon dioxide to obtain sodium hydrogen carbonate. The sodium hydrogen carbonate is slightly soluble in water, so it precipitates out as solid. Secondly, now sodium hydrogen carbonate is separated by filtration, dried and heated.

Answer 2

$Na_2CO_3 + 10H_2O$ → $Na_2CO_3.10H_2O$

Explanation:

Washing Soda  [Properties]

• It is a white, odorless powder
• Its chemical formula is $Na_2CO_3$
• It is chemically known as sodium carbonate
• It absorbs moisture from the air [hygroscopic]
• It' solubility in water is high and forms strongly alkaline water solution

Preparation of Washing Soda

The process by which Washing soda is prepared is Solvay’s process.

Solvay’s process - In this process sodium chloride, ammonia and carbon dioxide are reacted in water. Carbon dioxide is liberated from calcium carbonate and ammonia is recovered from ammonium chloride by calcium oxide that is left behind.

In the first step, sodium bicarbonate is obtained which is then converted to sodium carbonate on supplying heat.

By re crystallization of sodium carbonate washing soda is prepared.

The chemical equation is as follows -

$NaCl + NH_3 + CO_2 + H_2O$ → $NaHCO_3 + NH_4Cl$

$2 NaHCO_3$ → $Na_2CO_3 + H_2O + CO_2$

$Na_2CO_3 + 10H_2O$ → $Na_2CO_3.10H_2O$