What would we do without baking soda and baking powder? These two leavening agents play an important role in baking. Baking soda is also so useful in many other ways.
I did a post on all the useful things you can do with baking soda, besides cook with it. This stuff is really amazing. It is important to use it while it is still fresh. Here are some "fresh tests."
Baking Powder Fresh Test
Add 1 tsp. of baking powder to 1/3 cup hot water
Mixture should bubble immediately
Baking Soda Fresh Test
Add 1 tsp. baking soda to 3 T. vinegar
Mixture should fizz up quickly