Baking soda vs. baking powder
Both baking soda and baking powder are leaveners, which means they make cakes and muffins rise. So what's the difference?
Baking soda is pure sodium bicarbonate. Not only will baking soda fluff up your muffins, it can also put out a grease fire, clean your teeth and deodorize your carpet. When you cook with baking soda, you need to balance it out with an acid like lemon juice or buttermilk. Otherwise, your muffins may have a bitter, soapy flavor.
Baking powder, which usually comes in a can, is a combination of baking soda and a few other ingredients, most notably cream of tartar, a dry acid. Out of baking powder? Make your own by mixing one part baking soda with two parts cream of tartar.