Dropping funnel
Encyclopedia
A dropping funnel is a type of laboratory glassware
used to transfer fluids. They are fitted with a stopcock
which allows the flow of to be controlled. Dropping funnels are useful for adding reagents slowly, i.e. drop-wise. This may be desirable when the quick addition of the reagent may result in side reactions, or if the reaction is too vigorous.
Dropping funnels are usually fitted with a ground glass joint
which allows the funnel to fit snugly onto, e.g. a round bottom flask. This also means it need not be clamped separately.
Pressure-equalizing dropping funnels have an additional narrow-bore glass tube from the bulb of the funnel, to the ground glass joint around the stem. Without means to equalize the pressure between a sealed receiving flask and the bulb of the funnel, the flow of fluid will rapidly come to a halt.
Laboratory glassware
Laboratory glassware refers to a variety of equipment, traditionally made of glass, used for scientific experiments and other work in science, especially in chemistry and biology laboratories...
used to transfer fluids. They are fitted with a stopcock
Stopcock
A stopcock is a valve used to restrict or isolate the flow of a liquid or gas through a pipe.In Great Britain a stopcock, not to be confused with a gate valve or a DiCiaccio branch, is used to prevent flow of water into a domestic water system. There are usually two stopcocks for a home...
which allows the flow of to be controlled. Dropping funnels are useful for adding reagents slowly, i.e. drop-wise. This may be desirable when the quick addition of the reagent may result in side reactions, or if the reaction is too vigorous.
Dropping funnels are usually fitted with a ground glass joint
Ground glass joint
Ground glass joints are used in laboratories to quickly and easily fit leak-tight apparatus together from commonly available parts. For example, a round bottom flask, Liebig condenser, and oil bubbler with ground glass joints may be rapidly fitted together to reflux a reaction mixture...
which allows the funnel to fit snugly onto, e.g. a round bottom flask. This also means it need not be clamped separately.
Pressure-equalizing dropping funnels have an additional narrow-bore glass tube from the bulb of the funnel, to the ground glass joint around the stem. Without means to equalize the pressure between a sealed receiving flask and the bulb of the funnel, the flow of fluid will rapidly come to a halt.
See also
- Separatory funnelSeparatory funnelA separatory funnel, also known as separation funnel, separating funnel, or colloquially sep funnel, is a piece of laboratory glassware used in liquid-liquid extractions to separate the components of a mixture between two immiscible solvent phases of different densities Typically, one of the...
s are similar in shape and design, and may be used as dropping funnels. They do not have the ground glass joint at the stem.