Baking soda is the common name for which chemical compound?

Baking soda is the common name for sodium bicarbonate, a compound with the chemical formula NaHCO₃.

It is a white crystalline salt made of sodium ions and bicarbonate ions. In baking, sodium bicarbonate reacts with an acid—such as vinegar, buttermilk, cream of tartar, or citric acid—to release carbon dioxide gas. Those bubbles expand in the oven and help give cakes, biscuits, quick breads, and soda bread their lift. Baking powder contains sodium bicarbonate plus one or more dry acids, so it can work without an acidic ingredient already being present.

The name “bicarbonate” comes from an older naming system, not from the modern formula’s structure. The mineral form is called nahcolite, and sodium bicarbonate can also occur in trona deposits. Baking soda is different from sodium carbonate, commonly called washing soda, which is more strongly alkaline. It is also different from sodium hydroxide, a caustic chemical used in industrial processes.