No, baking soda is not a suitable substitute for baking powder in a recipe. Baking powder consists of a combination of baking soda and acid, along with a neutralising agent. Baking soda is an alkali, and it must react with an acid in order to produce carbon dioxide, which serves as the leavening agent in baked goods. On its own, baking soda cannot sufficiently perform the same function as baking powder.