Baking soda is a great item to have for longer-term storage. Not only is it important for cooking old, dry beans (see information on cooking old, dry beans here), but baking soda can also be used for cleaning, as a toothpaste substitute and as a laundry boost. Baking soda is also a great leavening agent and is an important ingredient as such in many recipes.
Baking soda has a long shelf-life.1 Steer clear of those small cardboard boxes in which baking soda is often packaged. Instead choose baking soda in #10 cans or repack it into a PETE container for ideal storage life. A typical #10 can contains 576 teaspoons.3 I also store baking powder and yeast as a part of my longer-term storage. All store well in cool, dry conditions.2
1 - LDS Church News
2 - USU Extension
3 - Emergency Essentials