Sodium bicarbonate (IUPAC name: sodium hydrogencarbonate), commonly known as baking soda or bicarbonate of soda, is a chemical compound with the formula NaHCO3. It is a salt composed of a sodium cation (Na+) and a bicarbonate anion (HCO3−). 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. Nomenclature
Because it has long been known and widely used, the salt has many different names such as baking soda, bread soda, cooking soda, and bicarbonate of soda and can often be found near baking powder in stores. The term baking soda is more common in the United States, while bicarbonate of soda is more common in Australia, United Kingdom and Ireland. and in many northern/central European countries it is called Natron. Abbreviated colloquial forms such as sodium bicarb, bicarb soda, bicarbonate, and bicarb are common.The word saleratus, from Latin sal æratus (meaning "aerated salt"), was widely used in the 19th century for both sodium bicarbonate and potassium bicarbonate.Its E number food additive code is E500.The prefix bi in bicarbonate comes from an outdated naming system predating molecular knowledge in reference to the two molar equivalents of carbon dioxide (known as carbonic acid in the ancient chemistry language) that potassium hydrocarbonate/bicarbonate releases upon decomposition to (di)potassium carbonate and to potassium oxide (potash).
The modern chemical formulas of these compounds now express their precise chemical compositions which were unknown when the name bi-carbonate of potash was coined (see also: bicarbonate). Uses
Cooking
Leavening
In cooking, baking soda is primarily used in baking as a leavening agent. When it reacts with acid, carbon dioxide is released, which causes expansion of the batter and forms the characteristic texture and grain in cakes, quick breads, soda bread, and other baked and fried foods. The acid–base reaction can be generically represented as follows:
NaHCO3  +  H+   →   Na+  +  CO2  +  H2OAcidic materials that induce this reaction include hydrogen phosphates, cream of tartar, lemon juice, yogurt, buttermilk, cocoa, and vinegar. Baking soda may be used together with sourdough, which is acidic, making a lighter product with a less acidic taste.Heat can also by itself cause sodium bicarbonate to act as a raising agent in baking because of thermal decomposition, releasing carbon dioxide at temperatures above 80 °C (180 °F), as follows:
2 NaHCO3 → Na2CO3 + H2O + CO2When used this way on its own, without the presence of an acidic component (whether in the batter or by the use of a baking powder containing acid), only half the available CO2 is released (one CO2 molecule is formed for every two equivalents of NaHCO3). Additionally, in the absence of acid, thermal decomposition of sodium bicarbonate also produces sodium carbonate, which is strongly alkaline and gives the baked product a bitter, "soapy" taste and a yellow color.