COOKING SODA (SODA EDIBLE)

Sodium bicarbonate or sodium hydrogen carbonate is the chemical compound with the formula NaHCO3. Sodium bicarbonate is a white solid that is crystalline but often appears as a fine powder. It has a slightly salty, alkaline taste resembling that of washing soda (sodium carbonate). The natural mineral form is nahcolite. It is a component of the mineral natron and is found dissolved in many mineral springs.

Since it has long been known and is widely used, the salt has many related names such as baking soda, bread soda, cooking soda, and bicarbonate of soda. In colloquial usage, its name is shortened to sodium bicarb, bicarb soda, or simply bicarb. The word saleratus, from Latin sal æratus meaning aerated salt, was widely used in the 19th century for both sodium bicarbonate and potassium bicarbonate. The term has now fallen out of common usage.

History

The ancient Egyptians used natural deposits of natron, a mixture consisting mostly of sodium carbonate decahydrate, and sodium bicarbonate. The natron was used as a cleansing agent like soap.

In 1791, a French chemist, Nicolas Leblanc, produced sodium carbonate, also known as soda ash. In 1846, two New York bakers, John Dwight and Austin Church, established the first factory to develop baking soda from sodium carbonate and carbon dioxide.

This compound, referred to as saleratus, is mentioned in the famous novel Captains Courageous by Rudyard Kipling as being used extensively in the 1800s in commercial fishing to prevent freshly-caught fish from spoiling.

Production

NaHCO3 is mainly prepared by the Solvay process, which is the reaction of sodium chloride, ammonia, and carbon dioxide in water. Calcium carbonate is used as the source of CO2 and the resultant calcium oxide is used to recover the ammonia from the ammonium chloride. The product shows a low purity (75 %). Pure product is obtained from sodium carbonate, water and carbon dioxide as reported in one of the following reactions. It is produced on the scale of about 100,000 tonnes/year (as of 2001)