Flask Logo Organic Chemistry at CU Boulder

Stir Motors

Stir motors are devices which contain a large magnet under a heavy, chemical resistent flat surface. The magnet is spun by an electrical motor. The organic chemistry teaching labs have several different styles of stir motors, two of which are shown in the photo below.

Stir Motors

Each has a knob on the front which controls how fast the magnet spins. Although they look durable, stir motors can be damaged if mistreated. If they are dropped, especially on their side, the shaft which controls the magnet can become bent, and the stir motor will no longer spin. They must protected from water, since this would ruin the electrical circuitry. The cords are susceptible to damage: do not drop chemicals on the cords, and keep them away from hot surfaces. Always unplug the units by placing your hand directly on the plug and pulling firmly; do not grab the cord and yank it from the socket.

The stir motor on the right, the round one, is especially susceptible to damage if dropped on its side. It also actually has two parts, the motor and a plate on top of it. If it does not have the plate on top, the spin bar spins out of control.

Stir Motor with plate removed

If a flask containing a stir bar is placed on top, the stir bar will spin in time with the magnet.

Stir Motor stirring a stir bar

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