You know I have been there and I am sure other people have too. You are right in the middle of baking and you realize you are missing baking soda but you have baking powder this often happens to me. However through my cake decorating class I discovered you can make other baking substitutions with other items. See the picture below. If you are ever in a pinch you may just have everything you need so that you don’t have to make an emergency run to the store. Real Simple also has some great suggestions for other baking substitutions that I recommend checking out as well.