Here's how it works:

* Baking soda (sodium bicarbonate) reacts with an acidic ingredient (like buttermilk, lemon juice, or vinegar) to produce CO2.

* Baking powder contains baking soda along with an acid (like cream of tartar) and a drying agent (like cornstarch). The acid and baking soda react in the presence of moisture to release CO2.

The CO2 bubbles expand within the batter or dough, creating air pockets that make the baked goods rise and become light and airy.