What is the difference between baking soda and baking powder?

Explanation

Both baking soda and baking powder are leavening agents. Baking soda is pure sodium bicarbonate. When baking soda is combined with moisture and an acidic ingredient (e.g., yogurt, butter milk) the resulting chemical reaction produces `CO_2` gas bubbles that causes baked good to rise. Baking powder contains `NaHCO_3` , but it includes acidifying agent (cream of tartar) already, and also a drying agent (usually starch). Baking powder is available as single-acting baking powder and as double-acting baking powder. Single-acting baking powders are activated by moisture, so we must bake recipes which includes this product immediately after mixing. Double-acting powder reacts in two phases and can stand for a while before baking.