(a) Describe how washing soda is produced starting from sodium chloride (common salt). Write equations of all the reactions involved.(b) State whether an aqueous solution of washing soda is acidic or alkaline. Give reason for your answer.
(c) What is meant by saying that washing soda has detergent properties?
(d) Mention two important uses of washing soda (or sodium carbonate).

Washing soda is produced from sodium chloride in the following three steps:

Step 1: A cold and concentrated solution of sodium chloride called brine is reacted with ammonia and carbon dioxide to obtain sodium hydrogen carbonate
$NaCl + NH_3 + H_2O + CO_2 → NaHCO_3 + NH_4Cl$

Step 2: Sodium hydrogen carbonate formed is separated by filtration dried and heated. It further decomposes to sodium carbonate
$2NaHCO_3 → Na_2CO3 +  CO_2 + H_2O$
Anhydrous sodium carbonate is called soda ash

Step 3: Soda ash is then dissolved in water and recrystallized to get washing soda crystals containing 10 molecules of water of crystallization
$Na_2CO_3 + 10H_2O → Na_2CO_3.10H_2O$

(b) An aqueous solution of washing soda is alkaline as it turns red litmus to blue.

(c) Washing soda has detergent property as it can remove dirt and grease from dirty clothes.

(d) The two important uses of washing soda (or sodium carbonate) are given below:
  • Used as a cleansing agent
  • Used to remove the permanent hardness of water


Simply Easy Learning

Updated on: 10-Oct-2022


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