And that attitude is exactly the reason you're bombing the class. Look man, chemistry (at that level) is NOT hard. I got 99% overall in both grade 11 and 12 chem, and missed about 1/3 of the classes at that. You know how I did that? Because chemistry is an awesome science in that it is extremely logical. This means that there is little that you need to memorize, you just need to understand it. Once you understand, it's very straight forward. (As opposed to say, biology which requires a lot of memorization, or physics, where even though the concepts are straight forward, you can apply them in an extremely complex manner.
Besides, it really isn't as useless as you think, because trust me, odds are very good that at your age you don't really yet know what you're going to do in the future. For all you know, you'll turn around one day and decide you want to pursue a career, and while it probably wont be as a chemist, odds are not too bad that you'll need a chemistry course or two.
Is there anything specific giving you trouble?