Baking soda is used as a leavening agent in cakes, quick breads and biscuits. It requires acidic ingredients such as buttermilk, lemon juice or molasses to activate it. Many recipes call for 1/4 teaspoon of baking soda per 1 cup of flour used, but this varies widely. Without a leavening agent, your baked goods will be heavy and dense. If you notice a bitter aftertaste when using baking soda, try reducing the amount slightly.