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?

Has this happened? You're getting ready to bake a few dozen cookies. You’re pulling out the ingredients, and you see it calls for baking powder and baking soda. But you only have one. Now you’re ...