Pressure Equalizing

A pressure equalizing funnel (also known as a dropping funnel or an addition funnel) is a form of laboratory glassware used to transfer liquids. It is equipped with a stopcock (glass or PTFE) that allows the transfer to be controlled. It's useful for gently introducing reagents, such as drop-by-drop. This can be essential if the reagent is added too quickly and causes side reactions, or if the reaction is too intense.