What is the main difference between baking powder and baking soda?

Baking powder contains both an acid and a base, which is the fundamental reason it can act as a leavening agent in baking without needing an additional acid. This duality means that when baking powder is mixed with liquid and heated, it can produce carbon dioxide gas, which causes doughs and batters to rise. The presence of both components allows for a more controlled leavening process, making it suitable for recipes that do not include acidic ingredients.

In contrast, baking soda is purely a base (sodium bicarbonate) and requires an acid to activate it in order for it to produce carbon dioxide. This knowledge is crucial for bakers to understand how to correctly use these leavening agents, as substituting one for the other can lead to less desirable results in baked goods, affecting texture and rise. The other options either misrepresent the nature of baking soda or introduce incorrect attributes related to sweetness, which are not relevant to the chemical properties or functions of baking powder and baking soda.