Needless to say, this is not a really deep question, but it has pinched me when baking. What is the difference between baking soda and baking powder? I think I read some years ago in a “Hints from Somebody” column that baking powder is baking soda with cream of tartar in it. I would think that just combining these two ingredients would be easier than creating and marketing a new product. Any ideas guys?
Baking soda is sodium bicarbonate (NaHCO3).
Baking powder is a combination of baking soda plus a few other things, most importantly a dry acid.
Go here:
http://users.rcn.com/sue.interport/food/bakgsoda.html
I’ve wondered about this myself and now we know.
Baking powder does usually have cream or tartar in it. Cream of tartar releases carbon dioxide when it makes contact with water or milk. So baking powder acts as a leavening agent while plain baking soda doesn’t.
“Never use baking soda in place of baking powder” is an old rule of housekeeping. Having once followed a %$#* misprinted recipe, I understand why.
You might mix your own baking powder if you knew the exact proportions, but it doesn’t seem worth the trouble. Ready made baking powder is inexpensive and long lasting.
Baking powder has a dough rising property to it, and baking soda doesn’t.
Almost like {b}ESP**
Maybe if I hadn’t used the Preview!
Oh well! 
Thanks every one! 
Thats one item off my Questions List (Next: Why is a postmortem on a human called an autopsy, but the same thing on an animal is called a necropsy?)
Gremlin, I’ve done the baking soda/powder mix up myself, it does suck. 
Hi Wyvern.
As mentioned above,the only difference is that baking soda is pure sodium bicarbonate while the other contains cream of tartar(potassium bitartrate which is weakly acidic).
However 2 things to consider.
1)Even pure baking soda decomposes partially in a hot oven to release some carbon dioxide.
2)If there’s acid in the food,that will also cause the soda to release carbon dioxide.So maybe lemon tarts will be a better choice for baking soda than plain old bread.
Citric acid and baking soda can be used to create your own baking powder but,
1)Too much acid can give a sour taste,too little may not be enough.
2)It’ll fizz rapidly and most of the CO2 escapes before baking even commences.Gradual fizzing(as caused by cream of tartar)is what gives the ‘holes’.