In laboratory chemistry, it is possible to mix a solvent and several solutes by means of an instrument called a magnetic stirrer. This, by exploiting the magnetic field on which the container of the substance is placed, allows it to be mixed without the aid of rods or external stirrers. The instrument that enables this process is extremely common in the laboratory, and is called a 'magnetic stirrer'. The stirrer reacts with the magnetic field and, as a result, is rotated within the container. There are advantages for which it is more convenient to use the magnetic stirrer, and the magnetic stirring rod, than the same process performed by hand. Firstly, the stirrers are chemically inert and can be cleaned easily. Moreover, if necessary, the magnetic stirrer allows a mixture to be stirred for long periods of time.
With the same stirring speed, what differentiates the effectiveness of stirring is the shape and size of the stirrers. It is therefore necessary to select the appropriate type of stirring rod according to its use.
Shape of anchors
There are in fact several different types of hooks. The smallest models measure only a few millimetres, while the largest up to a few centimetres. Anchors are generally coated with Teflon or, less frequently, glass. Glass is usually used to mix alkali metals and alkali metal solutions. As previously pointed out, these materials are chosen for this purpose because they do not react or contaminate the mixture in which they are inserted, being chemically inert. Their shape is usually oval or spherical, although there are various models with different shapes. To name a few alternative models, it is possible to find cross, spool, star and triangular models. Each of these shapes is suitable for a different purpose, depending on their weight, size and the surface area that comes into contact with the mixture to be mixed during the process. In addition, it is possible to point out a further feature of the stirrers: they have a disc around their centre, on which they rotate when pushed by the magnetic stirrer. This is often present in the most common models: spherical and oval.
For the removal of the anchors, a rod equipped with a magnet in the end section is often used. This allows the rod to be retrieved once it has been inserted into the container. This type of rod is referred to as a 'stirring rod'.