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? Mention two important uses of washing soda (or sodium carbonate).

Washing soda is produced from sodium chloride

Step 1: A cold and concentrated solution of sodium chloride called brine is reacted with ammonia and carbon dioxide to obtain sodium hydrogencarbonate

NaCl + NH3 + H2O + CO2 → NaHHCO3 + NH4Cl

Step 2: Sodium hydrogencarbonate 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 → Na2CO3.10H2O

• An aqueous solution of washing soda is alkaline because it turns red litmus to blue
• Washing soda has a cleansing and detergent property thus it removes dirt and grease from dirty clothes
• Used as cleansing agent

Used to remove permanent hardness of water