â—‡ Baking powder is a major ingredient in cakes. â—‡ This baking powder is a mixture of baking soda(sodium bicarbonate) and tartaric acid. â—‡ Sodium bicarbonate is a base which when heated or mixed with water releases carbon dioxide. â—‡ Sodium salt of acid â—‡ Carbon dioxide produced during the reaction causes the cake to rise to make it soft and spongy.