a Describe how washing soda is produced starting from sodium chloride common salt Write equations of...

Question

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

Accepted Answer

Washing soda is produced from sodium chloride in the following process:

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 + NH₃ + H₂O + CO₂ → NaHHCO₃ + NH₄Cl

Step 2: Sodium hydrogen carbonate formed is separated by filtration dried and heated. It further decomposes to sodium carbonate.

2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O

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.

Na₂CO₃ + 10H₂O → Na₂CO_3.10H₂O

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

(c) Washing soda has a cleansing property thus it removes dirt and grease from dirty clothes. These add to the detergent properties of washing soda.

(d) Washing soda can be used for:

Used as a cleansing agent.

Used to remove the permanent hardness of the water.

Lakhmir Singh Solutions Class 10 Chemistry Solutions for Exercise in Chapter 2 - Chapter 2 Acids, Bases and Salts