Chemistry

19. Properties of Sodium Hydrogen Carbonate.
(i) It is white crystalline solid.
(ii) It is sparingly soluble in water.
(iii) Its aqueous solution is alkaline in nature due to hydrolysis. The solution is weakly basic.

This solution gives yellow colour with methyl orange (indicator) but no colour with phenolphthalein.
(iv) On heating, it loses carbon dioxide and water forming sodium carbonate.

(v) When it comes in contact with H₂SO₄. It gives CO₂ which is used in fire extinguishers.
2NaHCO₃ + H₂SO₄ → Na₂SO₄ + 2H₂O + 2CO₂
20. Uses of Sodium Hydrogen Carbonate .
It is used as antacid (medicine) under the name soda bicarbonate to neutralize excess of acidity (hyper-acidity) in the stomach.
(ii) It is an ingredient of baking powder which contains NaHCO₃ and tartaric acid. When baking powder is heated, sodium hydrogen carbonate decomposes to give CO₂ and sodium carbonate. CO₂ causes bread and cake to rise. Tartaric acid helps to remove bitter taste due to formation of Na₂CO₃.
(iii) It is used as additive in foods.
(iv) It is used in making aerated soft drinks.
(v) It is used in fire extinguishers because it forms CO₂ , when reacted with H₂SO₄ surrounds the combustible substance which helps in extinguishing fire.
(vi) It is used for production of carbon dioxide.