Baking soda does indeed lose its potency over time. If you unwittingly let it expire, your next fluffy cake or bread recipe will emerge from the oven as dense and heavy as a hockey puck.
By storing it in a dry, air-tight container, baking soda should last for up to 18 months. You can find out whether or not a box of it is still good by performing this simple experiment:
Combine 1/2 cup of very hot water with a splash of vinegar, then stir in 1/4 teaspoon baking soda. If the mixture bubbles up, your soda is fine to use. If you don't see bubbles, that means you'll have to start anew.
Check out the slideshow above for 20 recipes that will help you use your baking soda up in time!
For more baking information, check out How to Bake the Perfect Cookie and The Difference Between Baking Soda and Baking Powder.