Baking soda = sodium bicarbonate = a base Baking powder = a base + a (dry) acid (+ an anti-caking agent) Baking soda lowers acidity of foods. Baking powder, h

Baking soda = sodium bicarbonate = a base Baking powder = a base + a (dry) acid (+ an anti-caking agent) Baking soda lowers acidity of foods. Baking powder, however, will create air bubbles whenever exposed to moisture. ("Double-acting" versions create a second wave of bubbles after being heated to around 150F. This is actually kind of a Big Deal.)