Baking Powder is a rising agent for baked goods. If substituting for baking soda you will need 4 times the quantity. Ensure you purchase a gluten free, no aluminum brand. Alternatively, you can make your own baking powder; 1 teaspoon of baking powder is equal to 1⁄4 teaspoon of baking soda and 1⁄2 teaspoon of cream of tartar. Note, that they should only be combined when preparing your recipe.