Class 10 Science

Baking Soda (NaHCO3 )

Baking soda and baking powder are important chemicals and are used for various household and industrial purposes. On this page, you will learn about preparation, characeristics and usages of baking soda and baking powder. These notes are based on the chapter Acids Bases and Salts from NCERT book based on CBSE syllabus.

Baking soda is another important product which can be obtained using byproducts of chlor-alkali process. The chemical name of baking soda is sodium hydrogen carbonate (NaHCO3 ) or sodium bicarbonate. Bread soda, cooking soda, bicarbonate of soda, sodium bicarb, bicarb of soda or simply bicarb, etc. are some other names of baking soda.

Preparation of Baking Soda

Baking soda is obtained by the reaction of brine with carbon dioxide and ammonia. This is known as Solvay process.

NaCl + CO2 + NH3 + H2O ⇨ NH4Cl + NaHCO3

In this process, calcium carbonate is used as the source of CO2 and the resultant calcium oxide is used to recover ammonia from ammonium chloride.

Properties of sodium bicarbonate:

  • Sodium bicarbonate is white crystalline solid, but it appears as fine powder.
  • Sodium hydrogen carbonate is amphoteric in nature.
  • Sodium hydrogen carbonate is sparingly soluble in water.
  • Thermal decomposition of sodium hydrogen carbonate (baking soda).
  • When baking soda is heated, it decomposes into sodium carbonate, carbon dioxide and water.

2NaHCO3 + heat ⇨ Na2CO3 + CO2 + H2O

Sodium carbonate formed after thermal decomposition of sodium hydrogen carbonate; decomposes into sodium oxide and carbon dioxide on further heating.

Na2CO3 ⇨ Na2O + CO2

This reaction is known as dehydration reaction.

Use of Baking Soda

  • Baking soda is used in making of baking powder, which is used in cooking as it produces carbon dioxide which makes the batter soft and spongy.
  • Baking soda is used as antacid.
  • Baking soda is used in toothpaste which makes the teeth white and plaque free.
  • Baking soda is used in cleansing of ornaments made of sliver.
  • Since, sodium hydrogen carbonate gives carbon dioxide and sodium oxide on strong heating, thus it is used as fire extinguisher.

Baking powder

Baking powder produces carbon dioxide on heating, so it is used in cooking to make the batter spongy. Although baking soda also produces carbon dioxide on heating, but it is not used in cooking because on heating; baking soda produces sodium carbonate along with carbon dioxide. The sodium carbonate; thus produced; makes the taste bitter.

2NaHCO3 + heat ⇨ Na2CO3 + CO2 + H2O

Preparation of Baking Powder

Baking powder is the mixture of baking soda and a mild edible acid. Generally, tartaric acid is mixed with baking soda to make baking powder.

NaHCO3 + C4H6O6 ⇨ CO2 + H2O + Na2C4H4O6

Uses of Baking Powder

When baking powder (mixture of baking soda and an edible acid) is heated, the sodium carbonate formed because of heating of baking soda neutralizes after reacting with tartaric acid and sodium tartarate salt is formed. The smell of sodium tartarate is pleasant and taste is good. This makes the cake or any other food tasty.

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