While staying at my grandparents’ house last weekend, I was craving pancakes—until I opened the baking cupboard and found a jar of baking soda with a label from the early 2000s. Could it still work?

Baking soda and baking powder are both common leavening agents for quick breads, cakes, cookies, and more. Both are critical in making doughs or batters rise, but they are not the same thing and ...