Please read the thread about baking soda, and baking powders. Baking soda is bicarbonate of soda, and is a salt. It is in the alkalye side of the PH table and reacts with acids. Generally, if a recipe calls for baking soda, it also calls for some acidic ingredient such as cream 0f tartar, buttermilk, sour cream, cream cheese, yogurt, vinegar, or something citrus.
Also, ratios are important. Alkalye materials are usualy bitter, soapy, or salty in flavor, while acids are sour to the taste. To understand what baking soda does, mix 1 tsp. of baking soda with 4 oz. of water. Then either go out to your car and pour this slurry onto the white powder surounding the battery teminals, or add a capful of vinager to the container containing the slurry. The liquid will begin to fizz energetically as the acid and alkalye react to each other and release Co2 and sulphur and Co2 into the atmosphere.
Baking soda and soap, both alkalye or base materials are often used to neutralyze acid contaminated skin.
Both are caustic, or more clearly, destroy materials by through the exchange of electrons in molecules, either adding or removing them from the original molecule, thereby changing the structure of the original molecule, usually disolving it into the liquid and releasing gasses into the air. It is the release of Co2 which is trapped by the protiens in batters and doughs that leaven the bread, cake, or whatever.
So there is a brief exerpt on what baking soda, and in turn what baking powder is.
Goodweed of the North