In A Nutshell
You probably have both in your kitchen cupboards somewhere, and you might even actually use one or the other with some sort of frequency. Baking soda is the more basic of the two, a white powder that’s also known as sodium bicarbonate. Baking powder, even though it looks like almost the same white stuff, is actually baking soda with an acidic ingredient mixed in.
The Whole Bushel
As it turns out, Mum was right. Baking really is a science, and baking soda and baking powder are both special chemical compounds that bakers depend on to make sure everything turns out right.
Baking soda is a simple sodium bicarbonate, created from soda ash (or sodium carbonate), and it’s made in one of two ways. Mixing carbon dioxide and ammonia with table salt creates soda ash. Alternately, it also comes right from an ore called trona. The soda ash is is dissolved with carbon dioxide, and the condensation that drips out is baking soda.
Baking powder is actually the same stuff with another ingredients. When baking soda is combined with a weak acid such as tartaric acid, sodium acid pryophosphate, or acid calcium phosphate, it forms baking powder. If you run out in the kitchen, baking soda can be mixed in equal parts with cream of tartar to form baking powder.
While both are used in baking as their names suggest, the chemical reactions that come when they are mixed with liquids and exposed to heat make them far from interchangeable.
When baking soda is used on its own, part of its carbon dioxide is released into whatever baked good it’s a component of. Without an acidic substance to balance it, it turns cakes and cookies yellowish and gives them a bitter taste. And perhaps of more concern, plain baking soda will react with stomach acid to release the rest of its carbon dioxide content and create some major discomfort.
Baking powder, on the other hand, is balanced with an acid component to negate these unwanted effects. The combination of the sodium bicarbonate and the acid creates a less alkaline final product, so it doesn’t leave the bad taste that baking soda alone does. It also regulates the release of the carbon dioxide, which helps to ensure a steadier rate of reaction. In baking, this means that baking powder used as a leavening agent to help make bread and cakes rise will be more reliable.
When a recipe calls for baking soda to be used as the leavening agent, there’s usually some type of acid in the ingredient list as well. Buttermilk, lemon juice, and molasses all react with baking soda to remove the bitter taste and regulate the release of gas into the final product. Essentially, baking soda is only used when it’s in a mixture that will allow it to act like baking powder.
Baking soda has some properties that make it much more versatile around the house than baking powder. In its natural state, soda ash acts on its surroundings to balance the levels of acids and bases. This means that it’s excellent at removing odors from the air, as it doesn’t just cover them up, but instead reacts with airborne particles to bring whatever strong acid or strong base that’s causing the odor to a more neutral level. It’s mildly abrasive (baking powder has a much softer texture), so it also makes an excellent cleaner for delicate surfaces.