My bottle of Potassium Bromide has turn into a bottle of white rocks. I'm guessing that it taking in some moisture. Can I bake it in the oven or the microhondas or should I buy a new one?
You can bake it if you want, but if you can get it out of the bottle grinding it is easier. You can buy one of those cheap coffe grinders with blades and you will get it done in a jiffy. And you can use the girnder for other chemicals if you wipe the cup well.
Caking doesn't always occur because a chemical has taken on water. Take a sample, weigh it, bake it and weigh it again. This way you can see if it is wet.