The difference between dropping funnel and separating funnel

The dropping funnel can be divided into a normal pressure dropping funnel and a constant pressure dropping funnel according to whether the air pressure of the upper and lower liquid surfaces is the same when dropping. According to the container shape of the dropping funnel, it can be divided into a spherical dropping funnel and a cylindrical dropping drop funnel. The atmospheric dropping funnel is composed of a frosted glass stopper at the upper end, a container in the middle, a two-way connection at the lower end and a pipe handle. The biggest difference between the dropping funnel and the separating funnel is the pipe handle. The pipe handle of the dropping funnel consists of two parts. The lower handle of the atmospheric dropping funnel is composed of a short glass tube and a spherical long glass tube. The main functions of the spherical dropping funnel are:

1. Control the drop rate of the liquid when preparing some gases (especially toxic gases), thereby controlling the reaction speed, especially when some reactions are relatively violent, smoke is generated in the container during the reaction, or colored gases are prepared, such as chlorine in the laboratory (especially When potassium permanganate reacts with concentrated hydrochloric acid to produce chlorine gas), nitrogen dioxide, manganese dioxide catalyzes the decomposition of hydrogen peroxide to produce oxygen, and laboratory produces acetylene and other gases, it is not convenient to observe the speed of liquid dripping in the reaction vessel. Reaction rate, the concept of green chemistry is to prevent and control the reaction first, instead of adjusting if the reaction is too fast or too slow. The structure of the lower end of the dropping funnel determines that the liquid is added dropwise during the gas preparation, which can be very convenient. The speed of droplet dripping was observed at the spherical shape of the lower pipe handle.

2. For some reversible reactions, by continuously dripping the liquid and distilling out the reaction products, the equilibrium is constantly moved toward the target product. In the experiment, the lower end of the dropping funnel should be extended below the liquid level. In the current ground glass instruments, whether it is a normal pressure cylindrical dropping funnel or a constant pressure cylindrical dropping funnel, the lower end is a double-layer casing, and the inner tube is slightly longer than the outer tube, which is mainly used for organic reactions. For the dropping of liquid, the outer tube is equipped with a grinding mouth, which is used to insert the reaction container to seal the contact, and at the same time, it plays a certain role in the fixing of the dropping funnel. The structure ensures that the liquid is added dropwise instead of flowing along the wall of the reactor, which is convenient for observing the dropping speed of the liquid. The reaction rate can reduce side reactions. If a ground separatory funnel is used, since the handle at the lower end of the separatory funnel is a single-layer glass tube, the liquid will flow into the reaction vessel along the wall when the liquid is dripped, which is not conducive to the operation of the experiment, and may reduce Slow reaction rate or reduced yield.

The dropping funnel and the separating funnel are obviously different in structure, and they have their respective uses. The main function of the spherical separating funnel is to quickly shake the mixture and let it stand for separation. For some gas preparation experiments with mild reactions, For example, the reaction rate of zinc with dilute sulfuric acid is measured. However, for the preparation of chlorine gas in the laboratory, the catalytic decomposition of hydrogen peroxide to produce oxygen, nitrogen dioxide and acetylene, and for some experiments that need to be inserted into the liquid below the liquid level, it is not appropriate to use a spherical separatory funnel instead of a spherical dropping funnel. with spherical dropping funnel