PTFE flasks usually have the appearance of a round belly and a thin neck, which is clearly different from a beaker. Its narrow mouth is used to prevent solution splashing or reduce evaporation of the solution, and can be used with a rubber stopper to connect other PTFE equipment. When the solution needs to react for a long time or be heated and refluxed, a polytetrafluoroethylene flask is generally chosen as the container. The opening of the flask does not have a protruding gap like a beaker. When pouring the solution, it is easier to flow down the outer wall. Therefore, a PTFE stirring rod is usually used to lightly touch the mouth of the bottle to allow the solution to flow down the outer wall.
Because the flask has a very narrow mouth, it is not suitable for stirring with a PTFE stirring rod. If stirring is needed, you can hold the mouth of the bottle and turn your wrist slightly to stir smoothly and evenly. If it is heated to reflux, a magnetic stirrer can be placed in the bottle and stirred with a heated stirrer. Flasks can be divided into two types: flat-bottomed flasks and round-bottomed flasks depending on their appearance.