If your favorite baking recipes suddenly stop turning out well, don’t panic! Your baking soda or powered may be expired. The shelf life for an open container of baking soda or baking powder is about six months, but here’s how to test for freshness to be sure. Take a teaspoon on baking powder and put it in a cap. Add 1/3 cup of hot tap water. If it starts to bubble, you are good to go. If not, time to replace it. As for baking soda, place 1/4 teaspoon baking soda in a cup and add two teaspoons of vinegar. Just like baking powder, if baking soda doesn’t bubble, it’s old and should be replaced.