Which of the following statements are true about washing soda? 1. Its chemical name is sodium hydrogen carbonate and its aqueous solution is basic in nature. 2. Its chemical name is sodium carbonate and the PH of its aqueous solution is more than 7. 3. It is used for raising of cakes while baking. 4. It is used for the removal of permanent hardness of water.

Washing soda

• Washing soda is obtained by heating baking soda and then recrystallizing the sodium carbonate.
• Chemical name - Sodium carbonate (Na2CO3)
• It is the combination of a strong base i.e., sodium hydroxide, and a strong acid i.e.: carbonic acid. Its aqueous solution lies in the basic range because of the presence of a strong base with a pH greater than 7. Hence, statement 2 is correct.

Uses

• It is used in glass, soap and paper industries.
• It is used in laundry to wash clothes.
• It is used for removing the permanent hardness of the water.
• Sodium hydrogen carbonate is Baking soda and it is used for raising cakes while baking. Hence, statements 1 and 3 are incorrect.

Permanent hardness of water

• When the salts of magnesium and calcium are present in the form of chlorides and sulphides in water, it is called permanent hardness.
• It can be removed by washing soda. Hence, statement 4 is correct.

Other ways to remove permanent hardness

• Chemical Process of Boiling Hard Water.
• Adding Slaked Lime (Clark's Process).
• Adding Washing Soda.
• Calgon Process.
• Ion Exchange Process.