[kristinak]

What is the chemical formula for cornstarch? Everywhere I look says "there is no exact formula", why is this?

[Arkcon]

What have you been able to find out on your own about corn starch?  There isn't an exact formula, but we can give you a good one, depending on your application.  Which, I assume, has something to do with this post: http://www.chemicalforums.com/index.php?topic=58933.msg211040#msg211040  You appear to have some application in mind, maybe you can tell us all, what you want to know, and for what purpose.

[kristinak]

In my gr 11 Chem class we had to make a cake and now we're talking about chemical components of baking powder and how they react as leavening agents. I'm having problems answering the question: "Baking powder is made up of three main components: baking soda, a dry acid, and a filler. Give the chemical name, the chemical formula, and the function of each component." I have found/determined the answers for the baking soda and somewhat for the dry acid, but I'm having trouble with the cornstarch (which is what is usually used as the filler). I know that it is used so that the reaction doesn't occur prematurely, as for the chemical name and formula, well, I'm afraid I don't know and I haven't been able to uncover it on my own.

[Arkcon]

You're not going to find a simple, clear chemical formula like you did for baking soda -- NaHCO₃.  At least, I hope you found that formula.  But does have something like a formula, its just that we don't express it in a simple way.  Try and look up a definition of "starch".  The best job you can do in this regard won't be as concise as for the other chemical formulas, but once you're close, you'll see how almost good enough really is good enough for your question.  You can check your text book index for the definition of starch, do an online search, or even look it up in a typical English dictionary.  Let's see the best definition you come up with, and try to get a good answer for your question.

[kristinak]

Here's what I've discovered. Cornstarch is made of mostly
Amylose - C24H45O21 and Amylopectin - C30H52O26
at a ratio of 1:3

[Arkcon]

What are amylose and amylopectin made of?  How are they different from one another?  How are they the same?  Most important:  how are they the same and different from one another in a way that does not match how baking soda and tartaric acid are?

What reactions does starch undergo?  Do those reactions match the acid base reactions of baking soda and tartaric acid?