I was looking through some AP Chem materials and tehre were a lot of questions regarding colors of solutions. Is there some handy dandy guide I can use to figure out the colors of various aqueous solutions? and also the colors of various compounds when the burn? We really don't touch upon this in my ap chem class and my book doesnt really speak of it. so i'm not sure where to find this information. also for anyone who took the AP Chemistry exam, what was the hardest part of the exam?