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?

Like baking soda, baking powder's main issue with expiration is all about its ability to help your baked goods rise. And there is a wonderful test you can do to see if can rise to the challenge, ...