Sodium Hydrogen Carbonate

Author: Hans Lohninger

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 70°C, 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.