All baking powders contain:

Baking powders are a leavening agent used in baking that typically contains sodium bicarbonate, which is a key component that reacts with acids to release carbon dioxide gas. This reaction is what causes doughs and batters to rise, resulting in a light and fluffy texture in baked goods.

Sodium bicarbonate acts as a base and, in the presence of an acid (which can be from the baking powder's other ingredients or added separately), it undergoes a chemical reaction. When moisture is added and the mixture is heated, the carbon dioxide generated from this reaction expands, producing the leavening effect.

While other ingredients like tartrate, phosphate, or acetate may be found in some specific types of baking powders, they are not universally present in all baking powders. Baking powders can be classified as single acting (which contains an acid that reacts with moisture) or double acting (which includes sodium bicarbonate and another acid that reacts upon heating), but sodium bicarbonate remains a constant component across these. Thus, it is accurate to say that all baking powders contain sodium bicarbonate.