Baking soda, or sodium bicarbonate, is a single ingredient. Baking powder contains baking soda along with an acidifying agent like cream of tartar and a stabilizer.
Baking soda reacts immediately upon contact with acidic ingredients to produce carbon dioxide bubbles, providing immediate leavening in recipes.
Most baking powders are double-acting, meaning they release carbon dioxide upon moisture introduction. During baking, they provide leavening throughout the baking process.
Baking soda's alkaline nature neutralizes acidic ingredients in recipes, balancing pH levels and aiding in browning and texture development.
Baking powder can usually be substituted for baking soda by adjusting quantities due to its inclusion of both acidic and alkaline components.
Baking soda is stable and has a longer shelf life, while baking powder may lose potency over time, requiring periodic replacement to maintain effectiveness in recipes.