What does baking powder have that soda not?

Here's the breakdown:

* Baking soda (sodium bicarbonate) is a base. It needs an acid to react and produce carbon dioxide bubbles, which cause baked goods to rise.

* Baking powder is a combination of baking soda, an acid (like cream of tartar), and a drying agent (like cornstarch). This means baking powder is already self-contained, so it doesn't need the addition of an acid.

Think of it this way:

* Baking soda is like a sleeping giant. It needs a little help (acid) to wake up and do its job.

* Baking powder is like a ready-to-go team. It has everything it needs to work on its own.

When to use each:

* Use baking soda when your recipe already has an acidic ingredient, like buttermilk, lemon juice, or brown sugar.

* Use baking powder when your recipe doesn't have any acidic ingredients.

Hope this helps!