I'm a rising Sophomore and by looking at the rules from past years, I would recommend that you take a Chem class first. But since you want to do it this year, basic stoichiometry is found in Chem 1 classes with some more advanced content in AP Chem. In my Chem class last year, we didn't learn any equilibrium, so I would assume that's AP Chem content. You could probably Google all the information if you want to do it that way, but try to ask the Chemistry teacher at your school if you have one. My Chemistry teacher was amazing last year and she will definitely help me this year because I haven't learned equilibrium yet.
Kennesaw Mountain High School, Junior
2013 Regional: 5th Rocks and Minerals, 12th Designer Genes
2014 Regional: 7th Rocks and Minerals, 12th MagLev, 5th Materials Science
2015 Regional State: 4th Air Trajectory, 4th Chem Lab, Protein Modeling, Wright Stuff