[Danizuni]

Hi! So I'm in AP chem and we did this lab last week where we had popcorn kernels (58.3 grams). We then popped them and the gram afterwards was 50.1. We determined that the percent composition of water in a kernel was 13.9%. Now our teacher wants us to write an empirical formula for this lab. I'm not sure what I'm supposed to write it on? I know starch (C6H12O6) should be there, and H2O. The rest I'm not sure. Could someone help me? Everyone else seems to be getting it with no problem but I don't even know what the formula should include.

[fledarmus]

Possibly the teacher is considering that any water present is in the form of waters of hydration? And that heating the popcorn is separating them from the starch?

In that case, using your definition of the starch, you might be looking at something like:

C₆H₁₂O₆·xH₂O  C₆H₁₂O₆ + xH₂O(g)

(Just be aware that starch is structurally more complicated than the formula you have written.)

This is a guess on my part - I can't think of any other line of reasoning that would invoke an empirical formula.