It's a flask with a flat bottom. It's used for containing liquids when you don't want to have to use a stand to keep it from tipping over.
Flat bottomed flasks are used for the same purposes as round bottomed flasks. The differences are: 1. the flat bottomed flask can stand alone, is more robust but not specifically designed to...
It is to hold different types of chemicals together to mix them, to make chemical reactions in liquid phase, to make titrations, etc.
A container in which you mix chemicals.
Collecting and mixing anything another vessel or apparatus puts out, such as a burette or distillation setup.
Flat bottom flasks (Erlenmeyer and Florence flasks) are used for heating all the time.