A glass stir bar, also known as a magnetic stir bar, is a small cylindrical-shaped bar made of magnetic material and coated with glass or plastic. It is a commonly used laboratory equipment that is placed inside a container filled with a liquid sample to create a rotating magnetic field that causes the stir bar to spin rapidly. This motion creates a vortex in the sample, which allows for uniform mixing and homogenization.
Glass stir bars come in various shapes and sizes, such as oval, polygonal, and cylindrical, and can be selected based on the specific needs of the experiment or application. The size of the stir bar should match the size of the container in which it will be used to ensure efficient mixing. The coating of the stir bar can also be chosen based on the chemical compatibility with the sample being stirred.
Glass stir bars are useful in a variety of laboratory applications, including sample preparation, titrations, and chemical synthesis. They are particularly useful in experiments that require constant and uniform mixing of a sample. Glass stir bars are also preferred over manual stirring as they can reduce the risk of contamination and minimize human error.
To use a glass stir bar should be placed at the bottom of the container filled with the sample and covered with a stir plate. The stir plate generates a rotating magnetic field that causes the stir bar to rotate and mix the sample. After use, the stir bar should be cleaned and stored appropriately for future use.