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Sodium Hydrogen Carbonate

Author: Hans Lohninger

Sodium bicarbonate (NaHCO3), or sodium hydrogen carbonate, also known as baking soda and bicarbonate of soda, is a soluble white crystalline compound, with a slight alkaline taste resembling that of sodium carbonate. It is found in many mineral springs, in natural deposits in USA and is mainly produced by the Solvay process:

NaCl + NH3 + CO2 + H2O NaHCO3 + NH4Cl

Sodium bicarbonate, when exposed to an acid, releases carbon dioxide and water:

NaHCO3 + HCl NaCl + H2O + CO2 (gas)

Above 70C, it gradually decomposes into sodium carbonate, water and carbon dioxide:

2 NaHCO3 Na2CO3 + H2O + CO2

It is used as an antacid to treat acid indigestion and heartburn. Sodium bicarbonate is also used to absorb moisture and odours; an open box can be left in a refrigerator for this purpose. Additionally, a paste from baking soda can be very effective when used in cleaning and scrubbing. Used in toothpaste, baking soda helps to gently remove stains, whiten teeth, and freshen breath.

It is used in combination with acidic compounds such as potassium hydrogen tartrate (cream of tartar) as a leavening agent in baking. Baking powder is a mixture composed mainly of NaHCO3. In addition, it contains anti-caking agents such as starch, and weak acids such as alum or tartaric acid. These weak acids react with sodium bicarbonate, releasing CO2 gas, which causes cake batter and bread dough to rise and produces the tiny holes in cakes and breads.

Sodium bicarbonate is used as a fire-suppression agent ("BC powder") in some dry powder fire extinguishers. It is a minor component of Purple-K dry fire suppression agent.




Last Update: 2011-03-18