--baking soda
n.
A white crystalline compound, NaHCO3, with a slightly alkaline taste, used in making effervescent salts and beverages, artificial mineral water, pharmaceuticals, and fire extinguishers. Also called bicarbonate of soda, sodium bicarbonate
--bak·ing powder (bkng)
n.
A mixture of baking soda, starch, and at least one slightly acidic compound such as cream of tartar that works as a leavening agent in baking by releasing carbon dioxide when mixed with a liquid, such as milk or water.