<p>Stoichiometry involves balancing chemical reactions and predicting products - it isn’t merely grams over molar mass. I was good AP Chem student (A in the class, 5 on the exam, 800 on the SAT II) and I know a year of intense honors chemistry was integral to my success in AP Chem. It looks like you may have stretched yourself beyond your limits. Take the B-'s and learn your lesson. Hopefully one bad class won’t destroy you.</p>