Baking powder and baking soda are two different things, so they shouldn’t be used interchangeably in baking recipes. Baking soda is 100% sodium bicarbonate and doesn’t contain any acids, so it’s recommended for recipes that already contain acids like buttermilk or cocoa butter. On the other hand, baking powder contains baking soda along with a type of acid, so it’s best used in recipes that don’t contain any acids.