I have learned what chemical reactions are. I have also learned what an endothermic reaction is, and what an exothermic reaction is. Something that I never knew before was the pH scale, and what a base is. I also learned that a lot of things are acids and bases but half of them aren't dangerous. What I liked the most about this unit was doing the Chemistry in a Bag lab. It was fun because our group's bag popped and we watched the bag warm up and blow up. What I like leaast about this unit was doing the lesson 1 and 2 study guide. Does anybody know any different bases and acids?