Baking soda is a base and hence it needs an acid to create a chemical reaction. So for cookies, cakes and muffins, etc to rise, baking soda has to be paired with an acidic ingredient like yogurt, buttermilk, vinegar, lemon juice, cocoa, cream of tartar etc. When it reacts with one of these acidic ingredients, carbon dioxide is released, expanding the batter and thereby giving the desired texture for the baked or fried goods.
