Which compound is commonly called baking soda?

Sodium bicarbonate is the compound commonly called baking soda.

Its chemical formula is NaHCO₃, showing sodium, hydrogen, carbon, and oxygen. It is a white crystalline solid that is mildly alkaline and is also known as sodium hydrogen carbonate or bicarbonate of soda.

In baking, sodium bicarbonate reacts with acids such as buttermilk, yogurt, or vinegar to release carbon dioxide gas. Those bubbles help doughs and batters rise. Recipes often pair it with an acidic ingredient because baking soda alone does not produce as much leavening gas.

Baking soda is different from baking powder. Baking powder contains baking soda plus one or more dry acids and usually a starch. Sodium carbonate, sometimes called washing soda, is another related sodium compound but is more strongly alkaline and is not the same household ingredient.