Mixer classification and use of magnetic stirrer

The agitator is one of the essential instruments for organic chemistry experiments. It can make the reaction mixture more uniform and the temperature of the reaction system is more uniform, which is beneficial to the chemical reaction, especially the heterogeneous reaction.

There are three methods of stirring: manual stirring, magnetic stirring, and mechanical stirring.

Manual agitation can generally be carried out by means of a glass rod, magnetic stirring using a magnetic stirrer and mechanical stirring using a mechanical stirrer. The magnetic stirrer is easy to install due to the magnetic stirrer, so it can be used for continuous stirring, especially when the reaction amount is relatively small or the reaction is carried out under closed conditions, and the magnetic stirrer is more convenient to use. However, the disadvantage is that the magnetic stirrer cannot be used smoothly for some viscous liquids or reactions with a large amount of solids participating or generated. In this case, a mechanical stirrer should be used as the stirring power.

The magnetic stirrer uses the rotation of the magnetic field to drive the rotation of the magnet. The magnet is wrapped in a small piece of metal with a layer of inert material (such as Teflon, etc.), or it can be made by itself: use a piece of 10# iron wire into a thin glass tube or plastic tube, and seal at both ends. The size of the magnets is about 10mm, 20mm, 30mm long, and there are longer magnetons. The shape of the magnets is cylindrical, elliptical and circular, which can be selected according to the scale of the experiment.
Mechanical agitator The mechanical agitator consists of three main parts: an electric motor, a stir bar and a stirring seal. The motor is the power part, fixed on the bracket, and the speed is adjusted by the governor. The stirring rod is connected to the electric motor. When the power is turned on, the electric motor drives the stirring rod to rotate and stirs. The stirring sealing device is a device for connecting the stirring rod and the reactor, and the reaction can be carried out in the sealing system. The efficiency of the agitation depends to a large extent on the structure of the stir bar, and the old-fashioned stir bar is made of a coarse glass rod. According to the size and shape of the reactor, the size of the bottle mouth and the reaction conditions, a suitable stirring rod is selected.

The magnetic stirrer is suitable for mixing and mixing relatively thin liquid substances. Here, a brief introduction to the magnetic stirrer should pay attention to several problems during the use:

First, when using it for the first time, check whether the accessories included in the instrument are complete, such as stirrer and power cord, etc.

Second, the speed should be gradually adjusted to high speed from low speed, it is best not to start directly at high speed, so as to avoid the stirrer being out of sync, causing jumping;

Third, it can't be heated when it is not stirred, and should be cut off when it is not working;

Fourth, the instrument should be kept clean and dry, especially not to allow the solution to enter the machine;

Fifth, if the stirrer is beaten or not stirred during mixing, please check if the beaker is stable and the position is positive;

Sixth, medium speed operation can extend the service life of the agitator;

Seventh, it is best to connect the ground wire when using it.

The above points are only for reference during the use.

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